Borrowing from the ever-quotable xerfilstyx again...
Knowledgeable (Ex): Swimming for so long in the River Styx has made xerfilstyxes some of the most knowledgeable beings in Baator. A xerfilstyx makes Knowledge checks for any Knowledge skills as if it had a minimum of 10 ranks in that skill. To surpass the 10-rank minimum, the xerfilstyx must assign more than 10 ranks to the skill as normal.
How about this?
"Activate Item" (Ex): A glyptar attached to a magic item makes Use Magic Device checks to activate the item as if it had a minimum of 10 ranks in that skill. To surpass the 10-rank minimum, the maedar/glyptar must assign more than 10 ranks to the skill as normal.