The general skill trees I am sure are imminently being released but maybe we could see -
Sword recovery, reclaim % of swords lost in battle, after each fight
Ranged recovery, reclaim % of ranged (bows/cannons etc) lost in battle, after each fight
Salvage expert, reclaim extra % of all lost weapons, after each fight
Battlefield medic, reclaim % of the units lost in battle, after each fight
Reduced travel time, reduce time to travel to/from adventures by %
Infiltrator, general ignores tower bonuses for all melee troops
Sharp shooter, general ignore tower bonuses for all ranged troops
Charge of the light brigade, general receives a bonus to cavalry units
Up close and personal, general and all melee units receive a bonus when only melee units are assigned
Stand off, general and all ranged units receive a bonus when only ranged units are assigned
Nearly immortal, general recovers from losses % faster