I have a +3 want of lightning and an unupgraded staff, and according to the wiki, I should end up with a +2 staff, but it says I’ll only get a level 1 staff. Why? I tried this on a different run, and it actually gave me an unupgraded staff, it’s not just the prompt being wrong. I’m playing the latest version of Shattered Pixel Dungeon.
That’s just not a workable plan. It’s very rare that you get any free upgrades this way. You have to already have put at least one upgrade scroll—and no more than 2—into the staff and then find some random +2 or +3 wand. Then, as long as the wand is a higher level than then staff, the staff will add +1 to the new wand you’re imbuing, but only if the staff is at least +1 itself.
You could wait to see what the wand maker gives you before you upgrading your staff to more than a +1 or +2, but I don’t bother. I just dump my first bunch of Upgrades into the staff as soon as I find them.