We have little problem here. The best cavarly in the game maybe is Khwarezm, but after they the best aren't crusaders but byzantine kataprachts, especialy general bodyguard, socalled ''immortals''. Crusaders has good cavarly, but they're unarmored completely - only in last part of middle ages west began arming also horses-but only general bodyguards.
In contrast Byzantine Empire has large contingents of heavy armored cavarly last time in time of Komnenian emperors - time of this mod.
Please keep this in mind.