Could be "The Runelords" series of books by David Farland.
One reviewer has this to say:
In Farland's world, there exists a magic that allows one person to
take a physical or mental quality from another.
For example, a common man can grant his strength to his Runelord,
living out his days as weak as a baby, while the Runelord becomes
twice as strong. Noble children receive gifts from their subjects at
birth: beauty, eyesight, brawn, wit or intelligence, hearing, and so
on. In return, the Runelords use their talents to govern their people
and defend them in times of danger.
The givers of the gifts, called Dedicates, live in luxury, pampered by
full-time attendants -- but without whatever qualities they bestowed
upon their lords.
So a woman who gives her beauty to a newborn princess lives out her
days as a dried-up hag. A man who bestows his flexibility on his king
becomes forever creaky and stiff. A gift of sight leaves one blind; a
gift of wit leaves one a drooling idiot.
In the Runelords Universe, the magical system is referred to as ‘Endowments’ - and it certainly fits your bill. But without additional details, it's hard to guess whether you've read any of these books. More on the series here and here.
Does anything look familiar?