Have headgear equip like boots, if it has a limited duration ability bind it to a key, the 'h' key is currently unused.
This enables helmets that up defense, targeting scopes, HUD units (warning of inbound projectiles to improve dodge chance), or vision enhancing visors (see farther away or only see selective items farther).
Have anything needing power here use power cells, reload from the equip screen, and be toggle-able.
I wouldn't mind a visor that would give me int2 for 1-2 spaces beyond my vision at 2 cells a second if it could be toggled. Heck you could make all of them but the +1 defense helmet exotic to fix the balance issue.