The "Son of the Horse-Lords" isn't so much to do with horse training. Rather, the "horse" was the throwback of Dalraidian pagan symbolism...ie-a horse was the standard, much like the eagle sits upon the USA flagpole. There were other such symbols, pigs, various birds etc.... I think we came out pretty well. Eachernthigearna (forgive my spelling) (horse lords) was distinctly Dalraidian (circa 450-850 AD)and separate from rival Picts until their unification under Kenneth MacAlpine (800's AD). The proximity of their lands to the Western Isle's no doubt lead to absorption/alliance benefits from the MacDonalds.