You're saying it's a Hook, and a blade?!

[Yeah actually, that's exactly what I'm saying.]

Face it, this just makes sense. Traversing an urban environment can be difficult. Not just on your legs or your arms, even your feet. No it's the fingers, they're what hold you to whatever it is you're trying to scale. So it just seams to fit that Assassins would create a tool to allow you to conquer that tower with the least amount of damage to those oh so delicate phalanges. [i.e. Fingers dude, fingers]

As with most cases, a tool is never used for it's original purpose only. Where a tool can become a weapon, or a weapon can become a tool is commonplace. Take dynamite for example, it was invented for the sole purpose of moving earth so that railroads could be created more efficiently. Now look how far we've come with that little red stick O' TNT.




 
So, the hook blade gives you the ability to move through the urban cityscape with added speed and grace, not to mention the ability to zip-line; [Yeah, zip-line, sweet right?] but that's not all it's good for. In a combat situation the hook blade is your ally, your fancy metal claw to manipulate your foe with. Either to disarm, evade, or disable. You foe will find the hook blade somewhat difficult to counter. You'll see a few of it's uses in action in the nifty video below.

[When I watch great action sequences like this... I think of Jason Bourne in a hoodie... oooh yeah.]

Later!
-Fox