Shield drum is a must that I know, I now take burst strike because I noticed pawns don't sprint in combat, so his mobility is fucking low and he can't tank if hes just walking around chasing mobs but that leaves the last skill...
If you don't have a ranged physical dmg you need a skill to knock the smaller enemies out of the air but pawns seem bad at using it , but you also REALLY want a skill that can hit hard on enemy weak spots (for downed dragons), the maw skill does massive damage on skeletons, downed enemies , goblins, humanoids etc so I like to use that, but I need to give my pawn a lot of mushrooms as he uses it too much and runs out of stamina
I also like cymbal onslaught just so he has more chances to get the rooster shield debuff up, and the last shield skill I keep empty because it's just more noise that prevents him from using the skills he should be using.