Sry to the developer, but this is stupid. I thought of checking them from the side as well, but only on eye-level not standing one tile above the object I wish to interact with. I noticed a similar behaviour in the colloseum where NPCs with bigger sprites only react if you talk to them from a specific tile. But that was definitely not the only instance.
EDIT: And inspecting the gauntlets in a shop doesn't say anything about them being breakable, so this is also no reliable source of information.