I really like the idea behind the 4E Weapon Groups, but some of the specifics seem poorly thought out. Categories like Light Blade, Heavy Blade, Bow, and Crossbow are good, but many of the others are too specific.
Do we really need Axes, Hammers, Maces, Flails, and Picks all as their own whole category? Most of these weapons are just variants of "heavy weight at the end of a stick", and most are used in very similar ways. Heck, it is pretty hard to tell a proper Warhammer from a Pick in the first place. With that kind of specificity, I am surprised Scythe and Whip aren't their own categories. I could imagine that it should be pretty easy to simplify those categories a little without imbalancing anything.
I think similar things could be said about separating out Staff, Spear, and Polearm... If a shuriken and a rapier are both counted as the same weapon type, then why can't a spear and a glaive both be in the same weapon type?