I think I'm on Kamagong's side here - there is something about SOME weapons that transcends the word "tool". I have hammers that I am particularly fond of, my father has a particular spade that I think we should bury him with, but there is something different about an object made solely as a weapon.
I have handled a lot of old swords. Some of them just sing to you on a deep, deep level. A 10th century Viking sword, still sharp despite a thousand years of rust, moved a lot of us near to tears. It wasn't just age, it was the feel in the hand. An 18th century broadsword felt light as a feather in the hand, but the slightest movement of the wrist and it begged you to cut with it. I've never felt a tool do that.
I am sure I'll love my ESEE 3 when it comes along, but it will always be a utility tool that doubles as a weapon, and in that it is just that bit less than something optimised for one purpose only. That is probably a good thing, walking around in the city today.
The thread about "Knives as weapons" really struck me because so many of the "Weaponized blades" of today ARE tools for killing. They're overengineered shanks. Gabe Suarez once said "Sometimes only ugly will do", and in that I think he is very truly missing the point.
I have a way-out-there psychological theory on this point, but I'm not about to state it on a picture thread.
I am not arguing with the genuine, OED/Webster's/Wikipedia, definition of a tool, or that weapons fall into that definition, but... "Damn it Jim, I'm a designer not an engineer", so words are a little different to me