The other annoyance of this very rigid "grid" system is that there's absolutely nothing between a 10' reach and a 5' reach, and a 5' reach and a 0' reach. The result being the details between weapons tend to be lost: A greatsword has the same reach as a dagger, a spear has the same reach as a longsword, etc. The result being that the distinguishing details of *WHY* someone would, realistically, choose the spear over the longsword are entirely lost: In real life, people chose spears because you could poke people with swords in the face while they couldn't reach you, even with "short" spears. And then there's the "small longspear", but that's another issue. The other amusing result is that, as a result, the combat system becomes entirely skewed for "medium" characters: Creatures with a 0' reach, because there's nothing between 5' and 0', are unable to achieve flanking, so two cats can't flank a single rat. This, of course, is absurd, as there's no reason to think that combat between critters of man-size and greater should be greatly more complex than combat between tiny critters. The end result is that this "grid" system promotes a reach mechanic where everyone has a reach in increments of 5'. There's no differentiation between anything of 5' reach, and heaven forbid you try to convert the system into metric: The net effect is that a halfling, which retains a 5' reach, suffers no disadvantage fighting against a human twice his size, whereas a human fighting an ogre twice his size eats an attack of opportunity if attempting to close with a normal 5' weapon. None of this would happen if you had more differentiation in reach, and thus could come up with a simple unified mechanic for determining any character's "reach": Weapon reach plus natural reach. It'd also remove the obvious abomination of the small longspear.