Melee Academy: Arm Lock in detail

Arm Lock as a combat technique has had a long and somewhat storied history in GURPS. As a result of a Forum thread (that I’m not going to link to here; it’s not the point) I went back and looked at commentary and execution on the technique since 4e came out in 2004.

It’s worth looking at – what actually happens in this technique.

Arm Lock in the Raw


So, firstly, I want to note that the use of standing arm locks has a long and well documented history. The pictures to the right are from Fiore, I believe (I really need to get the original works on that one). 

All of them invoke the same basic principles: put the joint in a position where further motion is injurious, and apply leveraged force such that your foe has very limited ability to actually apply his strength, both due to unfavorable angles as well as the position of the muscles and joints being difficult for the locked person to apply significant muscular force. Some of these moves are quite painful as well, though pain can be ignored and doesn’t impact everyone equally.

There are two ways to apply an arm lock in broad strokes – offensively and defensively, and this is reflected in the GURPS rules for applying them. In nearly every case, you first must be in contact, if not control, of some part of your opponent, most often the arm (but a shoulder lock can cut that pretty finely at times).

The broad strokes are basically

  • Make contact with the limb and secure a grip
  • Move either yourself, your foe, or both into the proper position; this can be quite dynamic depending on what both of you do
  • Apply force to the joint. Slow force will usually produce discomfort, then pain, then a break or (more likely) a dislocation. Fast “vibratory” force will break or dislocate the joint pretty instantly. 

There is often movement associated with such locks. This is both for positioning, as in step 2 above, or to get the heck out of the way of a return strike. You can see in the six images to the right that in five of them, the unlocked arm is basically out of play (the bottom left is a maybe/maybe not). The other option is some sort of leg stomp, though the availability of that move will vary widely depending on what both fighters are doing. No guarantees it can be done.

Defensive Standing Arm Locks with the Basic Set and Martial Arts

Some say this is the primary way that this technique is used in GURPS, and I won’t necessarily disagree. The basic pathway here is straight-forward:

  • Parry an incoming blow with Wrestling or Judo (or another skill if you have the right gateways, such as Technique Adaptation) when your foe throws his attack. This happens, obviously, on your foe’s turn.
  • On your own turn, step into close combat and attack using Arm Lock; your foe defends as usual. If you succeed, his arm is trapped and locked. This counts as being grappled.
  • Your foe may try and break free, but you’re at a significant advantage (+4 because he’s locked, and you’re at +5 if you have him with two hands), and every failed attempt nets another penalty.
  • On the turn after that, if you want, you can rock his world. Apply pain or injury, try a throw from a lock, or whatever. This is almost always a Quick Contest, but that may depend on the technique you use. You get ST bonuses for Wrestling and such, but it doesn’t look like the +4 for Arm Lock and +5 for grappling with two hands applies here – that’s only for breaking free. The injury is based on the Quick Contest, with damage equal to margin of victory
  • If your foe is standing, you can also employ the ridiculously nasty Throws from Locks (Martial Arts, p. 118). It’s resolved as a quick contest; win it and do swing crushing, plus damage bonuses for Wrestling if you have them, to the limb. This can include the neck, if you have him in a Head Lock. That damage is swing, x1.5 for hit location. It’s basically like hitting him in the neck with a shortsword in terms of injury, and flexible DR is not effective here. Yowzers.
Instead of injury, you can also apply pain with locks, which will impair him as well as hurt his ability to break free.
The real hell about this “defensive” arm lock is that while it does require a Wrestling or Judo Parry, there’s no additional penalty associated with this. You parry, and the next turn you can slap on that lock maneuver by rolling what is often (if you’re wise) your unarmed grappling skill +4 or +6 (the +6 is for those with GMs that don’t beat you with their +Peter V. Dell’Orto ‘s DMG for asking for Technique Mastery on Arm Lock, and allow it).
So let’s look at how that works, with a focused build:
Mr. Lockenkey: ST 12, DX 12, Judo-14 (DX+2), Arm Lock-18 (DX+6).

For 4 more points and GM permission, pick up Technique Mastery (Arm Lock) [1], Arm Lock-20 [2 more], and Power Grappling, which is so evilly useful I suggested eliminating it in TG.

We’ll put him against an unspecialized but not-sucky fighter.

Mr Dodeca: ST 12, DX 12, Combat Skills-12, HT 12.

Since we’re basing this fight on a defensive Arm Lock, I chose Judo. You’ll see why in minute. 

If he can, Mr. Lockenkey goes first and takes All-Out Defense. Technicall this would count as “Turn Zero,” and I’m granting him the benefit of that move, since that’s the way I’ve actually seen Arm Lock experts (in GURPS) behave.

Mr Dodeca [starts his turn] steps into close combat to punch (punches are Reach C!). He will hit 75% of the time.

Mr. Lockenkey actually hopes Mr. Dodeca does hit, and when he does, he does a Judo Parry, +2 to Parry for the All-Out Defense, and +3 for a retreat, because that’s one of the real benefits of Judo. His Parry is 15, so barring a critical miss, he’s going to successfully parry. He is now at Reach 1.

Mr Lockenkey [starts his turn] having parried Mr Dodeca’s punch, steps back into Close Combat to roll his Arm Lock-18, unpenalized, He chooses to make this attack Deceptive at -2, for -1 to his foe’s defense. 

Mr Dodeca has Parry-9 or Dodge-9. Depending on his skill, he may well elect to retreat, giving him a net (including the -1 for Deceptive Attack) Parry-9 with Wrestling, Sumo Wrestling, or Brawling, or Parry-11 with Boxing, Judo, or Karate. Dodging, he’ll be at Dodge-11.

Mr Lockenkey will capture the arm 2 times in 3 against a fighter that isn’t trained in one of the superior retreating skills, or 1 time in 3 against a foe that dodges or is trained.

If the arm is not parried, they are now in close combat, and Mr Dodeca can just punch, and Mr. Lockenkey’s defenses no longer benefit from the +2 for All-Out Defense, dropping him to Parry-13, still a successful Parry (and thus an opening for an Arm Lock) five times in six.

Let’s assume Mr. Lockenkey successfully captures and locks the arm, using both hands to do so.

Mr Dodeca [starts his second turn] now is in an Arm Lock. He must attempt to break free, using a Quick Contest of ST. He is ST 12. Mr Lockenkey is also ST 12 . . . but gets +5 for grappling with two hands and an additional +4 for having a lock on Mr. Dodeca. This is ST 12 vs. ST 21, and Mr. Dodeca has a 2% chance of breaking free. This is basically hopeless, and should not be attempted.

Mr Dodeca’s only opportunity here is likely to try and punch Lockenkey in the face or body. Per Martial Arts, p. 119, all attacks, not just the ones with the grappled body part, are at -4 when you are grappled. So he’s starting at Skill-8. He may well want to go Committed Telegraphic here, to bring that up to Skill-14, or even All-Out, for Skill-16 – targeting the face to try and force a knockout or stun. The only other option is to either AoA(Double) to attack and break free (but it’ll still be ST 12 vs ST 17). He AoA’s to the face for the attempted stun. 62% chance to hit, less the 50% chance Lockenkey gets for his Judo Parry-10 (no retreat, no All-Out Defense). So about 1 time in 3, Dodeca will hit the face. He will roll 1d-2 for damage, and 1/3 of the time, no damage will result. 2/3 of the time, enough injury will be done to invoke a shock penalty and stun roll, which will (again) only fail 1/3 of the time.

So, let’s see: 62% chance to hit, 50% chance to fail the defense, 66% to roll enough damage to cause a stun check, which fails about 25% of the time. Chance of success: 5%. Still better than the 2% chance of winning that quick contest, though.

Mr. Lockenkey [starts his second turn] is now able to apply injury via a quick contest of Arm Lock vs. ST or HT, which in this case are both 12. On the average, Lockenkey will, on the average do 6 points of damage, which is neither crippling nor a major wound. Success by 7+ will be both.

At that point, Dodeca is at -4 to ST and DX for breaking free in addition to -4 to DX for being grappled. He’s basically toast. Lockenkey will cripple his arm eventually (likely next turn).  

Lockenkey could also have invoked Throws from Locks, which is again Arm Lock-18 vs. Dodeca’s omnipresent 12. Swing damage of 1d+2 will result – actually less damage on the average than the lock., and here Wrestling at DX+2 would increase this to 1d+4, which on the average would cripple the arm.

Offensive Standing Arm Locks


Basically, this is the same thing, but first the aggressor has to grapple the foe. Not grapple the limb, but the foe. It’s perfectly cool to grapple the torso on your first turn, resist his breaking free (he’s at -4 to DX for being grappled, you’re at +5 to ST for grappling with two hands), then use Arm Lock to capture the arm (again, he’s at -4 to DX for being grappled), then injury as usual. It takes an extra turn for the attacker.

Ground Fighting


To do this well, you obviously need the Ground Fighting technique (MA, p. 73) and spend th 5 points required to buy it off completely. You also want Wrestling rather than Judo or Sumo Wrestling in this case. You won’t be doing a ton of retreating, and that ST bonus is sweet sweet goodness.

Here, you grapple your foe (likely on the torso), and perform a takedown, which is skill, ST, or DX vs. your foe’s skill, ST, or DX. In the example above, that’s Judo-14 vs 12, winning about 2/3 of the time. Once you both are on the ground, unless your foe is similarly trained, he attacks at -4 and defends at -3, while you attack at no penalty and defend at -1. Combined with the generic -4 for being grappled, and a downed foe attacks at -7 and defends at -5, which is a whole lot to overcome – even Skill-18/Defense-12 becomes Skill-11, Defense-7.

Parting Shot


This workup obviously doesn’t touch much on Technical Grappling. I’ll save that for another post. The differences are subtle but important, and worth going over in detail.

Ultimately, against a less-skilled foe, especially an unarmed one, the Judo Parry/Arm Lock combination is really, really dangerous. Where it falls down a bit is against weapons. Not a knife or Reach C weapon, since that will follow the pattern above (though only Judo defends at no penalty vs. weapons). The smart Reach 1 fighter (such as with a sword or mace) will keep his distance, likely using a combination of Wait and Committed Attack (Two Steps) to keep the Arm Locker from stepping into close combat to grapple with him and lock him up. Attack from Reach 1 and then step back to Reach 2, and he’ll have to do a Committed Attack (Two Steps) to chase you down. If you take two steps, attack at Reach 1, and back off to reach 3. Now even if he parries you, he can’t close in and lock you up without a pretty hairy move. Plus, of course, successful active defenses against Mr. Lockenkey do damage to his limbs unless he’s smart and wears armor on his arms.

Which he’d better if he want to try this sort of tricksiness in lethal combat.

The other thing that Dodeca and his like can do is bring friends. Note that even in the most advantageous case, Lockenkey is in close combat with Dodeca for at least two turns, inviting indefensible attacks from the rear, or forcing him to use movement or drop hands from his grapple to defend. You can only parry once per limb, so it’s possible to saturate defenses to the point where Lockenkey has to release his kraken or take hits.

One thought on “Melee Academy: Arm Lock in detail

  1. This is a really great article and I will definitely have questions later, but I just wanted to comment to let you know I enjoyed this so much I am actually going to comment on the blog directly! Articles like this which help explain how to handle 'Grappling in GURPS for Blithering Imbeciles' are something that really really helps people like myself who have DMed grapplingless GURPS for 15yrs due to lack of comprehension can really get a hold on (pun intended!)

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