I don't like the way casting spells using higher level slots is implemented. I think that having a different item for the same spell using a different level slot is confusing and not very intuitive. I suppose this will go worse as you level up and gain more spells.
In my opinion it would be much better to have a single item for each spell, and then by selecting it you can somehow specify at which level you want to cast it. Perhaps by dragging the spell directly to the slot of the corresponding level or by clicking on the spell and then in the box of the corresponding level. It might need an extra 'click' but I think it's worth it.
In fact it could be very cool that after selecting the spell and the character performs the corresponding animation, you could select a higher level slot and the visual effects of the character's animation would be amplified showing that a higher magic power will be released.
