Originally posted by DarthAnt66
tl;dr me then
Basically, as you said, Malak lacks material as a duelist. Ranking him higher than his feats portray him falls into the realm of conjecture.
His superior command over the Force doesn't necessarily grant him any edge in physicals either. He still lost to Revan in a duel twice on the Leviathan and was forced to resort to his Force abilities to end the engagement both times - against Kun, I'm not convinced he's powerful enough to simply ragdoll or Force stun him as he managed against Revan. Malak is also vastly more powerful than Bandon (easily one-shot range), yet the latter was stated to not have met his equal with a blade until Revan.
Kun on the other hand has an impressive and numerous assortment of feats and accolades that place him out of Malak's - or anyone Malak's fought - league in terms of raw skill, on top of his prodigious physicals that leave Malak in the dust, and a highly unorthodox fighting style and weapon, which to make it clear, is radically dissimilar to the traditional saber staff. Also, don't treat this as fact, since I have no source other than anecdotes, but I've frequently heard Kun's armor is made out of cortosis, providing him with margin for error should Malak's blade pierce his guard. It would also short out Malak's own weapon should he strike it, and given Kun's trickster mentality and Tràkata tactics, he might just intentionally leave an opening for Malak to exploit, only for the latter find out he's been duped fatally.
All in all, Kun's just the more impressive fighter, even if Malak is more powerful.