Frontline: It depends a lot on your playstyle. If you want to lead the charge, take heavy armor and a big fucking weapon so that you can kill people in 1 or 2 hits. I tend to charge in (full Pepega) so 3/3/0 Zwei let's me 1vX the best. If you like to play a bit safer, something stabby like spear or pole axe is good to poke from behind allies. It's easier to not hit teammates with a stab weapon.

For duels, pretty much any weapon is viable if you learn to use it well. Slow weapons have better drags, quick weapons have better accels, and range doesn't matter as much since you will likely be in each others faces.

I've been farmed by skilled players with cleaver who took advantage of the weapon's strengths.