Game loses track of torch usage.
If you have unequip a torch it goes back to the unused stack, resetting its mileage. The torch should either go on a separate stack or the stack of torches should keep track of half-used torches, which it does not at the moment.
(RM-1026 from redmine: created on 2013-12-06 by Michael Papageorgiou, , closed on 2013-12-16 by scrawl .)