Crossbow and Ballistic knife werent that hard too do, just play Sticks and Stones.
Assault shield was terrible to level, half the time, people shot you right through it, or you would line them up to block bullets and then youd die and see on the killcam they were to the side of you or everyone and there mothers was using semtex @_@
Executioner is really good actually, just draw them in very close and spam that trigger button.
All Things Require Sacrifice. http://i.imgur.com/FjisB.gif
Aside from the shield, crossbow, ballistic knife, and maybe executioner all the guns in the game are perfectly usable.
Truth. I would argue, though, that they are all useful in some situations (except for the executioner).. Crossbow is like a seconary sniper, fun to play with. Shield can protect your back. It is also the only non-EMP counter to a sentry gun that I know of Ballistic knife is a one hit instakill........
That said, they aren't tryhard guns, but they get the job done