I think I may have got myself stuck

[Ryastar]

Scrolls are mostly only useful for warriors since they allow you to cast the first level of a spell at no cost in mana. As a warrior, I always buy every scroll of gift I can find since you never know when you will need more res from your inquisitors. A few other spells are useful at first level too. So you only need to buy scrolls afterwards if they are useful at first level. In other words, the skill is only semi-useful, but since it comes with a bonus to mana as well, it's worth getting.