I wouldn't say that Cade 'beat' Krayt at his strongest. Fought him pretty well, but Krayt dark transfered him, gave him a vision through death, let his guard down, and Cade took advantage of that opening. Krayt was the superior duelist.
Still, Cade did a lot better than the first time they fought.
Cade did better in their first fight, Q. In that fight he lasted a number of pages, visibly and audibly strained Krayt and IIRC even scuffed his armor. In their second fight Krayt didn't take too much of an issue with him though it was inferably a good battle.
__________________ “The galaxy must experience the pain of death and the rapture of rebirth as I have. I will bring chaos. It is time for war.”
In the first fight, Cade was smacked in the face soon after engaged, then driven to his knees. The only damage Krayt took was from Cade's mom shooting him in the back with a heavy blaster, and even when Krayt was hit by that, Cade didn't think he could win, he just ran.
In the second fight, Cade avoided or defended more, plus there was an intermission where they dueled offscreen enough to move locations.