Why is the "grippy" a tool and not a weapon. What is it lacking to be a weapon?
Let me toss in my two cents on this question based entirely on the differences between my Griptilian and my Endura, and why those differences lead me to entirely agree with Hso on this point.
First, let me provide pictures of these two knives.
Griptilian 550
Spyderco Endura
I specifically like the Griptilian as a tool because of that blade style, which they refer to as a "modified sheepsfoot". In daily use, I find it quite handy, and I like it so much I bought a used mini-griptilian with that same blade shape off of the EDC forum. It's beefy, extraordinarily useful as a work knife, and I flat out love the AXIS lock.
On the other hand, look at the Endura. Let me use a technical term here: It's pointier. Still useful, but clearly it has the advantage over the Griptilian in terms of, you know, poking stuff.
If I had to get into a knife fight, and I was choosing either of these knives, I should think that 100% of the time I am choosing the Endura, simply because I can more easily penetrate with it. In terms of simple slashing, I would guess either would work, but I am still choosing the Endura. The other factor is that if I am going to knife-fight someone, I simply have more faith in the tried-and-true lockback than I do with the AXIS. This might be a completely unreasonable thing to say, but there it is.
Now, with that being said, I would not classify the Endura as just a weapon anymore than I would classify the Griptilian as just a tool. Certainly, bodily harm could be done by either just as easily as work could. I like them both, and I carry them both.
On a purely personal level, if I had to give up every single one of my knives except for one, I would keep the Endura. I own and will continue to acquire a variety of knives, but when it boils down to it, for my money the Endura is pretty much the cream of the crop. They are my Buck 110's, man. When I finally morph into a cantankerous old curmudgeon, I will be waving my Endura at those pesky kids with their ion-powered folding pocket katanas and will preach at them loudly and longly about how my 40 year old Endura pwns their faces.