Any idea how I might implement some form of fragmentation grenade in a low fantasy medieval setting?
Black/gun powder? Something magic?
In what way do you feel candles would be superior to a torch specifically? I'm not aware of any properties 'wax' might have, but you seem to be hinting that it might.
I don't think they're superior in general -- if you're just after good lighting or an ignition source they're inferior -- I was suggesting them as an additional item rather than a replacement for a torch. They have some potential uses that a torch might not though -- you might need a more subtle light-source, or multiple light-sources, or as mentioned they may be required for certain rituals. I didn't have any specific properties of wax in mind, but figured anything might make a potential spell ingredient. Wax could also be used to contain things or to coat something that would otherwise be dangerous to handle directly.
Interesting. Are you aware of any trope where this would be applicable?
Unfortunately I can't remember the specific example, but I do recall encountering a monster in an AD&D campaign which was vulnerable to glass weapons.