How about this as a very early idea: start with something like the Virtuix Omni that allows the player to freely move and rotate. Add 3 thin metallic pillars su

How about this as a very early idea: start with something like the Virtuix Omni that allows the player to freely move and rotate. Add 3 thin metallic pillars surrounding the device, going up to about 2m, which would rotate with the player. At 2 different heights on each of these pillars there would be a pully controlling a slightly elastic cord via fast acting actuators. The other end of each of these ropes would be connected to the sword controller. Most of the time, there wouldn't be much tension coming from the cords (other than perhaps representing gravity pulling on the sword's mass), but when a hit needs to be simulated, the right cords would rapidly tense, according to the simulated properties of the object being hit.