Re: How to make Martial Arts Credible in Fantasy Setting?
The answer is simple. It will be as credible as you allow your history to be. You may even be able to work into your story that the martial arts came from the elves themselves, and his teacher might have lived with them for a long time (prompting perhaps a plot reason for the main character to be searching for them). Alternatively, many of the japanese weapons came from farmers revolting against the rule of the samurai. Though the history is a little more complicated than that, many martial arts weapons come from that which woudl be found on a farm (staff for all manner of things, sai were used for putting seed holes in the ground, nunchaku rice threshers, etc).
If you create a credible history, then you can do whatever you wish. As to fight scenes, whatever the world, swinging a staff is swinging a staff.