NPC AI has been able to use consumables and items their inventory since the days of DOS 2.
While it's a neat detail, it's not exactly new.
And it's one of the advantages of having a a dynamic AI rather than a series of basic "IF - THEN" instructions.
It's something Swen VIncke talked about even in the post-mortem of DOS 2 at GDC.
EDIT - from minute 47 going on (but frankly the whole thing is worth a watch):
