Having simplified Defenses, I have been able to turn my attention to revised weapon groups.
There are no attack rolls in Phoenix, so the primary focus of a weapon group is the Damage dealt. It's only partially the total die value - it is also the size of the die. This is important to the feel of the weapon in play, because Phoenix dice explode. When a weapon should rely more on these critical events to do its damage, it should use smaller dice. When a weapon should rely less on critical events, it should have a larger die size.
Weapon descriptions themselves are left up to the players and the GM. The weapon must be made in a fashion that intends it to be used as a weapon; otherwise, it is either reduced in die size or considered nonproficient. Nonproficient weapons always do 1d6 and never gain a bonus from any attribute.
So, if a player wants an anime-sized scimitar, and the GM's okay with that, then so be it. It's still a 1-H Striking weapon. If a player wants to use nunchuks with his kung fu, then great. It's still Martial Arts.
As seen in this table, Finesse weapons - rapiers, daggers, and the likes - are an example of weapons that rely on critical hits. They use 2d4 as the base die, which means that an explosion will happen quite often compared to a 2-H Striking weapon. When an explosion does happen with a greatsword or a savage axe, though, the damage potential is amazing.
Crossbows are an interesting group, in that they do 1d10 damage with no attribute modifier. This represents the ease of use in training basic crossbow proficiency. Any peasant could learn to use a crossbow fairly effectively in a week's time. They wouldn't be an expert, of course, but base weapon groups don't represent that. They represent basic proficiency.
A class might offer the ability to have superior skill in any of these groups; for instance, a Conquestor can gain a bonus die size to Unarmed or 2-H Striking weapons. Similar examples will extend to crossbows in the future.
Martial Arts use Body, which is the combination of Strength and Dexterity. This makes it much harder to have a high value, because it requires two good scores instead of one. However, if both scores are very high, Martial Arts has the highest damage potential of any melee group.