Disenchanters can eat magical items for food like incantifiers do (i.e. draining the magic out of the item, leaving it as uncharged/cancelled/+0 or turning it into a mundane counterpart). This works for disenchanter pets, and for players polymorphed into them. Not specified whether this should give the player intrinsics.

Possibly, add a ‘magivore’ monster flag to represent monsters that can do this, though if only disenchanters are capable of doing this then it may not be needed.