Balance wise it's reasonable. The issue is that it replaces one way the spell was an annoying nuissance that engendered endless debates with a new way for it to be an annoying nuissance that engenders endless debates. Original formula annoying Guidance at least had a better ludonarrative (priest bestows minor skill blessing on friend, rather than priest invokes divine ward against friend's failure at last second but only up to a ten foot range). At the end of the day I'd rather it just be a little more overpowered and not slow down gameplay. Or not exist.