From the 4 runs I did, my damage rating is as followed
2H > Bow > Knives > Magic
The reason 2H is considered to be the best is because it deals huge damage that is also AoE. That's the advantage it has over all the other physical type as majority of them are single-target especially knives. Combined with Warlord and acting last (so you can group enemies for him), it's normal to see a 2H build kill 4-5 targets from full health in a single turn.
The best single-target damage source however, is bow thanks to Preempt buffed rage snipe and that you can stack Rage with Highground for a minimal of 1.8x damage bonus (1.5 Crit * 1.2 Highground) .When you consider that Adrenaline-Crossbow can hit twice while also having higher base crit than usual (like 1.8 * 1.2 for a massive 2.16 per highground crit on gears that already have about 25% more damage than bow), it's really ridiculous especially with Elven racial thrown into the mix.
