Actually, Swadian knights worked fine for me. Unless you are outnumbered too heavily and you have decent tactics, Khregits will not hit a given knight too often. I ususally lose 7-9 knights (wounded included) to 100 khregits if I have a knight-only army and am outnumbered about 3-4 to 1 (of course, good AI, full damage to everyone). Less when Khregits have less of an advantage.
The bigger the battlesize the better: more units means that two are more lucky to bump together. And once they do, the result is bad for a Khregit
Myself, I am on a spirited courser wielding a sabre and a shield. After the initial charge, Khregits scatter and I can cut them down one by one. Very rarely, courser might get killed, so I take one of dosens of Khregit horses running around. If you feel cheap, you can take horse of the first Khregit you kill - even if it gets crippled it is not yours
The problem occurs if you have infantry-cavalry mix. They will separate and get killed piecemeal. Nords are simply getting raped by khregits on plains.