On my post Melee Academy: Why I Don't See a Lot of Disarming, one of the commenters (TheOneRonin, posting as Unknown) said, in part:
"-Weapons are not significant DEFENSIVE threats. [. . .] Given that in GURPS defenses will most likely be lower than offensive skills, and given that often times, the PCs will be more skilled (sometimes significantly so) than their opponents, the chances of suffering damage when punch a guy with a knife are VERY low…almost negligible."
The idea that weapons are defensively weak as a threat versus armed attackers runs fundamentally counter to my own experience in GURPS. Not just in my high-skill Dungeon Fantasy game - it's run counter to my experience ever since GURPS started allowing successful parries to injure unarmed attackers.
The running comment in my game is that an armed character gets to attack on his turn, and then parry and attack for free on his unarmed foe's turn.
I figured I'd look at some of the numbers involved.
These rules come from Parrying Unarmed Attacks, p. B376.
Assuming an attacker steps into close combat and punches or grapples, or stays at reach 1 and kicks against a melee weapon-armed foe with no Deceptive Attack and no prior Feint or Setup Attack:
Skill-10 Defender: Parry 8. 25.9% chance to Parry, 37.5% with Retreat. On a successful Parry, 50% to successfully strike the attacker, 9.3% vs. Karate or Judo.
Skill-12 Defender: Parry 9. 37.5% chance to Parry, 50% with Retreat. On a successful Parry, 74.1% to successfully strike the attacker, 25.9% vs. Karate or Judo.
Skill-14 Defender: Parry 10. 50% chance to Parry, 62.5% with Retreat. On a successful Parry, 90.7% to successfully strike the attacker, 50% vs. Karate or Judo.
Skill-16 Defender: Parry 11. 62.5% chance to Parry, 74.1% with Retreat. On a successful Parry, 98.1% to successfully strike the attacker, 74.1% vs. Karate or Judo.
Skill-18 Defender: Parry 12. 74.1% chance to Parry, 83.8% with Retreat. On a successful Parry, 98.1% to successfully strike the attacker, 90.7% vs. Karate or Judo.
You're allowed to parry with any legal weapon against a melee attack (such as a kick) coming at Reach 1. You are also allowed any of your normal, legal defenses against a close combat attack on the initial turn your opponent steps in to attack you (see the GURPS FAQ, case 188.8.131.52).
Shields, by the way, make this worse. Canonically, all you need is a successful Parry, and a parry by the margin of the DB of a shield is still a successful parry. An attacker-friendly GM can just say you hit the shield instead, and inflict damage on it (and possibly yourself, if the shield is wooden or metal, see Hurting Yourself, p. B379), but a defender-friendly or rules-literalist GM is free to do both. Ouch.
Fencing weapons get a +3 to Retreat, too, not +1, so they push the Parry numbers down two rows. A Skill-12 Saber fencer has a Parry 12 with Retreat and succeeds 74.1% of the time, and has the same 74.1% chance of getting in a free attack.
- Each 2 points the attack trades off into a Deceptive Attack pushes the defender up a row (towards lower skill and chances.) For this reason, unless the attacker is constrained by time, it's always better to maximize Deceptive Attack even if it reduces your overall chance to hit. Better to hit with a penalty to be parried or miss than just hit and take your chances with a full parry.
- Given an extra action before striking to use for a Feint, each point of skill greater for the attacker is, on average, a -1 to the defender's chances to defend.
- Given both, every 2 point skill margin the attack has is at least a -3 to defend.
- Given high skills for both attacker and defender, the potential risks of attacking are high, but the potential to ram down defenses are also high.
For the defender, All-Out Defense (Increased Defense), with a +2 to Parry, is a good way to fight defensively. A Defensive Feint is a good call, too, if you have superior skill, since it forces foes to forgo Deceptive Attack. You need a higher relative skill to pull it off.
I'd argue here that this makes sense - a large disparity in skills makes for a heroic edge for the more skilled attacker. An unarmed attacker vs. a more skilled armed fighter is in real trouble. An unarmed attacker vs. an equally skilled armed fighter is a risky situation. An unarmed attacker vs. a much lower skills armed fighter is relatively safe. The unarmed fighter's potential edge is magnified by proper tactics (Feint, Deceptive Attack, etc.), which can be negated to an extent by proper armed defender tactics (Defensive Feint, exploiting Reach, All-Out Defend, forcing the unarmed fighter to Move and Attack, Wait, etc.)
Since my old GURPS 3e game, I have made the "free attack" from parrying into a half-damage attack. You roll normally, inflict half of that, rounded down (usual minimum of 1 on cutting, impaling, etc.) I was pretty generous for animals biting to get the -4 as if they had Karate or Judo. Even so, it was free attack city for armed defenders.
In my own DF game, I've expanded these greatly:
Punching vs. guys wielding swords
Now, there is one part of that comment I strongly agree with - if the attacker has significantly more skill than the defender, the risks above drop. But not by much - the only way to ensure you don't get hurt by a Parry is to ensure that the opponent cannot Parry. This post -
Melee Academy: Unarmed vs. Knife - covers methods to do that in more detail. Short version: Feint, and maximal Deceptive Attack.
But yes, whenever you privilege one side in an opposed situation, such as attackers having significantly greater skill than the defenders, that side will have an edge. Often a significant one. If that's coupled with further advantages (healing spells, superscience healing, good arm DR, weak foes, Extra Attack, a large skill gap, etc.) you are further making it more likely they can pull of the difficult task of going unarmed vs. armed.
That's really a system feature, not a bug - by default, around human norms, with modern realism rules, there is much to risk in going unarmed vs. armed. Also, by default, with equally matched foes at any skill level, unarmed vs. armed is a risky situation for the unarmed fighter. If you want to ensure the unarmed folks are in trouble, don't let them have too many advantages above their armed foes. A knife is no way to make up for a large deficit in skill or in special abilities. If you want to ensure unarmed isn't really a problem, you need to bolster what they get. It's cinematic, not realistic, but the tools are there to do it.
You can make it worse for the attacker - allow that "do I hit the limb?" roll even if the parry is failed by, say, 3 or less or even 5 or less (which pretty much means all parries), or just all parries that aren't critical failures. Don't penalize it versus Karate or Judo. Make failed unarmed parries allow both a strike to the parrying limb and the original target.(None of these has been playtested, by the way - my experience is that unarmed vs. armed is already really bad for the unarmed, but there are things you can do if you don't agree.)
You can make it better for the attacker, like I do - suggestions fill the Punching vs. guys wielding swords post.
And by the way, if you're feeling the pain for the unarmed striker/grappler, then I have some help for you there.
Unarmed DF Martial Artists
Now I recognize that my experience may differ from others. But my long experience in actual play is that GURPS is pretty nasty to unarmed attackers going against armed foes. I think the numbers above back that up. If you don't, well, I have suggestions embedded to change the odds.