Here's what I have so far, pretty simple and direct:
Cost of Power (CoP)
We treat Magic items in GSF as special, rare, and powerful. Every magic item possesses varying degrees of intelligence or will, and carrying multiple magic items can levy a serious cost on the power-hungry bearer. Before each game, players should tally up the Cost of Power scores for the magic items each member of his warband carries. Then each character with a CoP total greater than 1 rolls his Resolve against a TN equal to the CoP total. If the character succeeds on his check, he’s fine. If he fails, he starts the game at -1 Vitality, and if he suffers a KO, he also incurs a -1 penalty on any post-battle checks.
Lost Vitality from CoP checks cannot be healed by Regeneration, healing spells, or magic potions. It returns normally after the post-battle phase ends.
If the character still carries magic items in excess of CoP 1 at the start of the next game, he must make the check again.
Example: Tylak carries Glasses of Scrying (CoP +1) and a Greater Magical Long Sword (CoP +2) for a total CoP of +3. At the beginning of each game that he possesses these items he must make a TN3 Resolve check or start the game at -1 Vitality. If he winds up KO’ed or removed from play, he’ll also suffer -1 on his post-battle checks.