How about making the spellbind power a one-shot thing?
That is, the wand in your book is a blank slate, waiting for a spell to be bound to it, but once one is bound, that's it. the spell cannot be swapped out. You have effectively made a Wand of Teleport, or a Wand of Dissolve, or a Wand of Lightning Bolt.
That way you would get the power to adapt to the game situation you find yourself in, but do not have a completely mutable toolbox at your command for every time the game state changes.
That would work for me, I think.