Two musical instruments that are very popular/commonly encountered in Riskail that aren't necessarily so common hereabouts are the Theremin and the Diddey Bow.
Or check out Carolina Eyck's website for more Theremin goodness. It's not just for Trekkies.
A wide array of different variations of Theremin are very popular amongst the Jarpha who use entire dissonantly-contrasynchronized orchestras of the things in the production of their notorious operas. They also make use of a combination bagpipe-theremin instrument on the field of battle as a means of striking terror into their opponents. Unless you've faced them in mortal combat, the noise generated by these instruments is simply indescribable and best left to the imagination as that would be far less damaging than actually hearing one of the things being played. Veterans who've gone up against Jarpha units often opt for memory-editing to remove all traces of the experience, and the persistent nightmares caused thereby, once they've had their ears replaced or rebuilt.
These things are just plain cool as all get out and totally a DIY sort of instrument that is absolutely unique to the musician. The Siluroi and Lutrin Blues-bands feature a lot of Diddey Bows and homebrew variations on the basic idea. Johnny and Edgar Autumn are considered to be two of the best there is at playing a Diddey Bow, but opinion svary and they've only just gone on the road, so they have yet to make a name for themselves outside of the Estuarial Regions.