ToME Wiki(hopefully this is the right place to put this...)
Spellbinder doesn't let you reselect the spells when they're already selected. It's dangerous to unselect them by getting hurt. When you gain skill with Spellbinder, you will want to reselect them in order to have more spells in it. I made a patch to allow that ("Reselect the bound spells?"): http://webpages.charter.net/theswamp/isaac/s_meta--smaller.diff
Also some of its messages (or lack thereof) are ugly or confusing. And to be more intuitive they should be selected in the order they go off. I have a bigger patch that adds those and IMO improves the coding style ("Spellbinder cancelled"; instead of "With the spells: Healing Disperse Magic Fireflash", it says "With the spells Healing, Disperse Magic and Fireflash."): http://webpages.charter.net/theswamp/isaac/s_meta--bigger.diff
KhymChanur: While on the subject of Spellbinder, how about fixing it so that if you select a spell that it too high a level for you to bind, it will let you select a different spell rather than select one for you. Even better would be if spells you are unable to bind would be greyed out, so you'd know not to try to select them.
As for re-binding spells, how about if you cast Spellbinder when there's already spells bound, it tells you "There are already spells bound, do you wish to trigger them"? You could then trigger the spells to get rid of them, and then bind a new set of spells.