There are many very useful props in the Demon King's Claw Cave in "Dragon Quest III: HD-2D Remastered Edition". The first is the nap stick, located on 1F, in the small tunnel near the center of the floor. You can get it, and then the Thief's Bandana, which can be found on 2F in the last curved tunnel before the northern exit.
Where are the props in the Demon King's Claw Cave in Dragon Quest 3 Remake
The Ice Shield is a fairly useful shield, although it may be outshined by other shields you already have. Blizzard Blade is very useful for providing ice attacks to characters who don't have ice attacks of their own.