This is the one that I prefer. I think you have more leverage and control while tuning those many strings.
These are your standard tuning wrenches. Some people like them because they feel more centered in the hand while turning the tuning peg.
This tuning clip has an alligator clip that attaches to a tuning pin or hitch pin on the hammered dulcimer and a 1/4" plug on the other end for when you need to tune in a noisy environment. The external mic is the best way to tune but you'll need this when your in a room with other musicians.
This little erasure will brighten your strings by rubbing the tarnish off and keeping them shining and sounding like new.