Well, there is Ixil's Spike in ToB, and its a +6 Spear...
What I meant though, and what Morgan pointed out is the rarefication of +5 weapons or better. Why isn't there at least one weapon of each class that is able to hit all enemies? What if your character concept is a crushing mace barbarian, who has to wait until ToB to hit anything with the +5 Storm Star?
And the problem with IEEP and making weapons is that for me, I was not involved in BG2's planning stage, so I do not know the criteria used to balance the game. I absolutely abhor cheating in any form, and I like to play and/or conquer games on their terms. So I won't require the Celestial Fury +5, but it pains me not to accept...