What are the best instruments for making a fantasy/medieval theme? As far as I have gotten, the Grand Piano, Violin, and Cello make decent parts, but I would like to know what other people think are good ones.
Try harpsichord, and high sine for recorder or flute. You may also want drums. Perhaps harp to substitute a lute. I would also try smooth synth to fill in the vocal frequency range
Depending on the wealth of your band, you may instead want to do a more orchestral style with trombone and violin and pizzicato, and stuff like that.
If you are going for a more modern video game take on medieval don't be afraid to add jazz guitar and piano and really anything along with some of these listed instruments
Try basing your song of some actual 12th century medieval music for best results. I found an interpretation of 12th century arabic music once, I will see if I can find it again