There is a nexus here so he can improve his speed, and coupled with his expertise in lightsabers he should get a majority against either duelist. Exar hasn't faced a duelist who knows as many lightsaber forms and who Bane thought was the best duelist in the galaxy. That's above any feat or accolade for Kun or Krayt in terms of skill. What Kas'im lacks in actual showings of skill he makes up for in textbook knowledge and training ability