My guess is that if you're in factions, you'll be able to own one of the new dread war horses regardless of your taming/lore skills. No clue yet where we'll be fighting these guys and their controller owners, whether you will also have to be in factions in order to tame one, taming skill required to tame them, and rank your character has to achieve in order to actually ride one instead of just take it out of the stable and admire it. Also no idea what they do for "tricks" and no clue at all why anyone thought giving them that ability is appealing. Kind of turned my stomach when I read about it.
Have been studying the lists of pets owned by my faction tamers to see what to get rid of so they can own a dread war horse or at least take one long enough to train it for other characters. War horses are pointless on thief characters, even for bank-sitting thieves, because the pet names always show up on log-in. Kind of a bad thing if your thief likes to log into the game behind enemy lines.