spell casting imbued items and encumberance

[ano]

Yes, you can cast it twice with quickness for 10 fatigue per turn. I also don't know if it is a feature...
Btw, take a look at the Staff of Corrosion. Among the simple and cheap items it looks rather powerful and also you may cast quickness with some mage and not give the quickness item to commander. Requires a bit testing though. Buffing spells tend to target the most powerful creatures and quickness spell probably also behaves that way.