Why max your staff to 15 when you can max it to 17?

It's actually possible to get a +21 staff -- but it requires a lot of luck. Get a wand +3, plus two other wands of the same type. At the troll smith, upgrade the staff to +1 and reforge the wands to get a +5 wand. Dump all upgrades on the wand to get a +20 wand. Imbue the wand to get a +21 staff. See https://lemmy.world/comment/10573988

Of an item in general? Example, a plate mail. +3 from grave, +2 from smith and +15 upgrade scrolls. Same for wand, except you actually have to get the wand from the old wandmaker. Lightning, freezing and disintegration are stronger. (Disintegration is technically equal, but it's instant and piercing, which I'd rather use)