UNDER THIS CUT ARE SPOILERS
Ok, the mech with the knife.... Might seem dumb, but think about it.... They get there, they have these awesome walking machines of death, and they get PWNED by a big panther. that figures out real quick how to take your gun away. What do you do? A second gun is kind of big and heavy, but they probably tried it for a while.... FAIL. what do you do now? Hey, can I get a knife for this thing? Like, a huge bowie knife.... then I can stab it when it jumps on me, and I don't have to worry about ammo and range and what to do after it takes my gun(s). Oh shit, this is awesome! Yeah, I'm keeping this sucker right on my hip from now on....eat metal death, giant six legged panther! For another angle, if you've ever watched any mecha-centered anime, when the gun runs out, or is destroyed, what does the gundam always pull out? A HUGE KNIFE OR SWORD. And then proceeds to kick much ass. Or think in Warhammer 40K terms; its a close combat weapon. And that's all I have to say about that.