I realize that this thread is old, but it's too quiet here lately...
The sword for me. We practice a sword art called cheong seok keohapdo (청석거합도). It is nominally Korean but is very heavily based on Muso Jikiden Eishin Ryu. The art contains 25 "hyung" (forms, kata, waza) and four "poomsae" (movement patterns that combine basics like the different cuts, parries/deflections, steps, stances, blood-shakes and resheathing).
"Keohapdo" is the Korean pronunciation of the Chinese characters (居合道) that are pronounced "Iaido" in Japanese.
Keohapdo practice is a very nice complement to our style of hapkido. Training in the art of the sword derives from the root art of our hapkido, Daito ryu aikijujutsu. Sword training is an integral component of Daito ryu training (their sword art is called Ono Ha Itto Ryu).
The principles of aiki are prominent in several koryu sword arts, and their presence in aikijujutsu probably derives from sword arts.