The horse lord & The demon lord by Peter Morwood 1983

The horse lord

Seeking vengeance on the enemies who have slain his clan, young warrior Aldric begins a quest for the one weapon of power that can destroy the magic of an evil sorcerer dead for five-hundred years.

The demon lord

Despite being abandoned in the land of his enemies, Aldric, last survivor of his clan, will not turn away from the perilous task he is pledged to complete. Allies ride to his aid, but even if he survives a madman's deadly sorceries and the precarious attentions of an omnipotent dragon, still greater evils await him on his dangerous quest.