I can’t remember too many plot details sorry but the book was about a travelling conquering alien race (that on the front cover were kind of dressed like knights in golden armour on horse like creatures) that destroys/enslaved other species across the galaxy. There was some interesting heraldry designs on the cover as well . I’m sorry I know this is vague! It may have been part of a series I’m sure there was at least a second book.
Thanks everyone for your suggestions, I was able to identify the novel as Exile's Challenge by Angus Wells.
Escaping a life of servitude under the evil Autarchy, a warrior, his beautiful wife, and a gifted Dreamer are refugees from the war-ravaged prison colony of Salvation. It was the young Davyd's dreams, magically bound to those of a far-off Seer, that guided their perilous flight to the land of the Matawaye. But even now they might not be safe. For a man whose gifts are eclipsed by Davyd's is looking for the perfect vengeance. Meanwhile, a renegade band of the Matawaye, forced out by their peaceable leaders, is wreaking havoc on Salvation. And there's worse to come. For the real threat has yet to descend on Salvation--and when it does, its bloodlust and magic could well mean the end of them all.
Exile's Challenge (Exiles, #2) - Goodreads synopsis
This is the cover I remember. There was heraldry symbols on the spine of the novel I think.