being able to hoard magic items and expend them for effects:
exhausting magic items to get some effects or completely destroying them for big one use effects
for potions you could sacrifice items to improve it
weapons bigger damage
armor bigger AC or hp
using the environment to make traps
scale up the dice for subclasses
revert the magical guidance back to the original one of a +1 bonus to SAVES per attunement, and lower this feature to level 10
you can give the addition that they can burn an attunement to instantly succeed a saving throw