I know that the amount of people that can do rune casting currently is roughly 1/10, but I think the base of runecrafting itself can be used for a samurai-type class.
If you remove visuals, make it 2D texture (A samurai sword does not have the 3D type movement as rune casting does while drawing 3D based runes), however it could still be somewhat used in 3D (for such attack like a classic super quick draw as swipe). Then make it only check a single line and order in a ‘combo like’ fashion. If you hit it right, your next attack with have a boost to the hit and maybe some affect. Because it is more combo moves, each swipe would do damage, so combo’s themselves would. The difficulty can be upped, with the addition of more realism, for swinging around the back of a person- such as the instance of a full 360 swipe to hit multiple enemies surrounding a person.
However, it could still be used in an exactly similar usage as current rune drawing - but using more of a sword/silvery/metal shimmer in the air (again, slightly less powerful power ups because the moves would be combos instead of just drawing in the air). However I would be great if it gained some addition of defense to by holding it on its side to block attacks. Samurai swords are capable of defense and attack in usage (in sword fights).