This was definitely an obvious one as far as ideas for additional weapons for Link go, so I'm glad it's actually happening and isn't just an extra feature, but a full weapon type with its own move set. The only other two characters I could actually imagine fighting while riding a horse would be Zelda and Ganondorf, but it's far more significant for Link to have it.
Hope Epona has some good mobility compared to many other weapons and characters. Obviously this is all simply preparation for the Cucco mode I suggested yesterday, where moving quickly will be crucial.