ToME WikiKhymChanur: Currently, items which can be activated when equiped/worn recharge over time while they're being worn. It might be interesting if some items recharged in different manners.
One other means of recharging would be by the player killing monsters. It could simply be a certain amount of monsters to kill, or depend on the levels of the monster, or how much experience was gained by killing them, or it could only count when certain types of monsters are killed. For activatable weapons, it could count only when the weapon is reponsible for the killing blow, like how sentient weapons gain experience. The difficulty with this means of recharging is having to deal with more than one equiped item which recharges by the method.
Another means would be to absord grid mana. While recharging, when you move onto a square that has grid mana, all of it is sucked into the item, and some portion of that mana goes into recharging the item. This would force the player to decide to choose between using inscriptions and using the item's activation.
Both of these methods would mean that the player couldn't sit on the surface, or in some safe corner of a dungeon, and just rest while the item recharges; s/he would have to do stuff while waiting for the item to recharge.
RavenRed: I like this idea. Other uses might be "Sacrifice Gold", "Be in Water", "Be in Lava", "Be in trees", "Be on Void Gate" and so on. You could also make it affect (for example) regeneration, hunger or life/XP drain. It could very much become a case of "Fire once, then retreat"!
LogrusMage: Other possibilities include giving it a U-menu ability that recharges it, so it recharges off the char's mana, or having it only recharge under specific circumstances (only at night, or only underground, or only in presence of sunlight (defined as lightsource that harms vamps)), or that gain a certain amount of charge when a particular trigger occurs, (like kills, but with other possible triggers) like teleporting, being hit with a particular attack type, etc.
TheFalcon: So my rod of trap detection will only work if I keep getting hit by nether balls? What fun :P
RedNaga: they could be *mana* balls! Even more fun!
RedNaga: i agree with the idea, in particular with the grid mana absorbition suggestion, but i would avoid making things too specific, unless the item effect is *really* powerful (more than most of the existing ones) - having an item only recharge on lava, for example, would be a real pain when dealing with some dungeons.
And, with relation to LogrusMage's idea about the U-menu power, i think it would instead be a great addition for a new spell (high-level recharge spell change?) - it would be a *very* costly spell which tap into the player mana to recharge the power of an item!