Weak against magic

Refers to a man or woman of short and portly stature. In many fantasy books movies and games, a dwarf/troll or the like, are highly susceptible to magic spells. An indirect way of calling someone a troll or a dwarf.

That woman is weak against magic. Surely her physical attack is quite strong.

-"So how was your date last night?"
-"Well, he'd be weak against magic, if that tells you anything."