blaze & blade help

any blaze & blade fans ?
hi all. hopefully you lot can help me with a few bits on one of my fav rpg’s. its blaze & blade and if had it since it was released way back in '98.

ive done it a few times, got all my spells (but not items) but there are a few unanswered questions & rooms that i need to find out. where iam stuck, is the old palace. ive killed the dark elf, and when i go into the transporter, i have 2 doors on my left & right. the right one is a healing chamber, and the left door cant be opened unless i have the key. i know where the key is cos iam standing next to a black chest (locked) which behind a door only an elf can open. the one thing i want to know is, how can i unlock the black chest?