There are some weird little bits in GURPS. Or at least, little bits I've always found weird. Here are two, plus a bonus musing.
Long Weapons & Occupied Hexes. You can attack through a friendly-occupied hex with a long weapon with no penalty, as this is part of the training with a long weapon.
This makes perfect sense for polearms, such as spears, halberds, and glaives. It makes some sense for two-handed swords, especially used to thrust. It makes pretty close to no sense at all for long one-handed weapons, like rapiers and jianns. So I sigh every time someone says, "Have the fencer stand in the back rank, she can stab through the front rank with her rapier!" I just can't see how this works without a lot of coordination by the front rank fighter, and even then, it's not as seamless as a two-handed overhand reach and stab down. It would probably make a huge amount of sense to say this rule only affects pole weapons and naturally two-handed swords while held in two hands (so you can't stick a second hand on your rapier for a long-distance stab.)
Thrusting (sword). Ever since Man-to-Man, GURPS has made the assumption that larger one-handed swords and all two-handed swords are, by default, blunt. Sharp ones are the exception.
I don't think that's true. But even if it is true, I think it would be so much easier if swords were assumed to be top-end models. So you'd have:
Broadsword ($600, thr+2/imp)
Blunt Broadsword ($500, thr+1/cr)
and so on for the other swords. It would save a lot of new player confusing, spare the "is it a thrusting sword?" questions on loot, every single time looting of swords happens, and save a lot of typing.
Small (weapon). Actually, on a related subject of names, I've had players complain about how heavy axes and maces are. Yet the weapon tables contain smaller versions. No one takes them, basically ever, because they want the biggest one with the highest damage. And then moan the weight is too high, historically or otherwise.
Which is probably true. But even if only a few 4 pound war axes and 5 pound maces were out there, it's worth including them on the weapon charts as actual historically available weapons if there were at least a few. I wonder, though, what if we renamed them?
Hatchet (2#, sw/cut)
Small Axe (3#, sw+1/cut)
Axe (4#, sw+2/cut)
Small Mace (3#, sw+1/cr)
Mace (5#, sw+2/cr)
If we had:
Hatchet (2#, sw/cut)
Axe (3#, sw+1/cut)
Heavy Axe (4#, sw+2/cut)
Mace (3#, sw+1/cr)
Heavy Mace (5#, sw+2/cr)
I think you'd have less complaints. "Hey, the heavy axe is really heavy!" Yeah, go figure. Or "I'll take a mace." "Want a heavier one?" "Nah, not worth it." instead of "Small mace? May as well take the normal one." The bottom end ones would still be heavy-ish, although not crazy - 24-28 oz tomahawks and hatchets are available for sale online, and covers and belt loops and such and rounding to save sanity would take care of a lot of that gap up to a round 2 pounds. And if you really need a Small Mace, use the Knobbed Club stats. A really big one? Go get a Gada or Maul. (Incidentally, the maul is only 14#. Know what we called the 16# sledgehammer at the gym I used to train at? The little sledgehammer.) Basically reset what the normal expected weapons are. Similarly you could do this with knives (make the small knife into Knife), although I see a lot of small knives anyway.
I'm sure I'd still get complaining (and probably will in the Comments section) that the weights are still too high. But I think they're close enough, reasonable, and you would see a lot more people using the "small" weapons if they were the normal, expected version instead.
ST and exceeding ST. Back in 3e, GURPS used to let you ignore the re-readying requirement on unbalanced weapons if you had +5 ST over the ST stat (then called MinST) over the weapon. In 4e, it's +50% over. That's nice, in that it's normalizing to ST 10 and then smoothly moving them up as the ST score of the weapon goes up. You got the same, say, Knockback, which was normalized to ST-2 instead of per 8 points of basic damage (something we tossed out years back in favor of just using straight-up ST or HP, which better represents difficulty shifting things with force and is way easier to deal with.)
But it's odd. A ST 12 weapon in 3e would need ST 17 to use without re-readying. ST 12 could lift 20% more than a ST 10 person. ST 17 could lift 70% more. But in 4e, a ST 12 person can lift almost 50% more than a ST 10 person, and ST 17 can lift almost 3x as much (and double that of the ST 12 person.) So in other words, in terms of raw lifting ability, raw ability to move weight around, 4e requires a lot more. I've wondered for a while if shifting that down (to 30% over, or merely +3 over ST in the interest of simplicity) would be better. It would bring the actual physical muscular strength needed to better control the weapon down to more reasonable levels. It wouldn't always work out to be exactly the same amount of lifting capacity change if you went with the plus, but it would be easier.
Those are just some little oddities that I see. Any that you folks want to comment on?