Well the sword was just an example. I would prefer a handsome one-handed sabre on horse myself - Zmeu that would indeed be Mr. Wolodyjowski's style .
Initially I was surprised to find I will not be able to use a spear on horse, however after some thought (and reading your posts above) I guess we should differentiate heavy, infantry two-handers (swords, spears or whatever) from specialised cavalry weapons. Since KH mechanism does not, a simplification of using only one-handers while riding a mount is in my opinion acceptable. Thanks for the input!

PS: Ish - on the contrary - as I used to ride horses for a short period I found your comment quite interesting.