The combat tree being in the universal section is the problem. Its a personal power growth tree, where the other 2 are transferable power. Dual accounts to make the ultimate fighter is just too obvious a way to work system. Sure they could make all of the tree's equal in-game power. Having an account for crafting and an account for actually playing is always gonna be superior thou.
They should move the combat tree to either archetype or have it in its own section. Dual accounts for Exploration/Crafting just doesn't have the same game impact so not much of a concern to me really. They could even add Skill arcs for other aspects like maybe leadership or mobility (faster riding, running, swimming, climbing). Basically a section for each type of power:
Personal Power: Combat, Leadership, Mobility
Transferable Power: Crafting, Exploration
Play-Style Power: Archetype's