As Fitz is walking near the school, he'll hear something making urgent, sharp trills for his attention. When he stops he'll see there is a particularly small spirit trying to catch up with him, and they are dragging something just behind them in the dirt.

Which, well, not the best way to treat a gift. Fitz will have to dust and grass off the guitar to see what it really looks like. Once it is in his hands, the spirit will clap, make an oooooh sound, and sit down on the spot in hopes for a performance.

And as Fitz plays his adoring crowd a few notes, he'll note the guitar sounds great and plays easily. Perhaps more notable, though, is it puts the spirit into a sense of calm so strong after only a song or two, it falls asleep. This effect is particularly strong on spirits (the smaller they are the more effective it is), though he will find it works similarly for other residents of Beacon, if they're willing to let it (in other words... with player permission).