hardest to use: k98, non scoped.
snipers, you have to have the right mindset, you need to pop around corners scope out knowing where to look, or camp from a distance.
rockets, even if you're no good with the rocket (i love me some rocket kills) have excellent secondary weapons - the carbine and c96(?) both are great close range, and the carbine is even reasonable at longer distances.
so, why the k98? Because it has none of the advantages of sniper (precision) and all of the disadvantages of SLOW bolt action.
If you don't agree, and have never played dod 1.3 before, spend a week playing it and you'll understand - for those that have, recall that in 1.3, the k98 has what seems to me a faster rate of fire, and more importantly, is a 1 hit kill weapon! having to shoot someone twice (in the upper body hit box) is an incredible disadvantage for the source k98, because unless you're fighting another k98 or a terrible assault player, you're pretty much done for... if the gun were still one hit, or were faster to use, or the ironsights made it that much better it would be good, and i'd say sniper to be hardest because you have to have patience... but alas, i vote for the k98. what an awful gun.