+res -def or +atk -spd for owain?

I'd say:
+res -def for offence (basicly using it as neutral)
+atk -spd for defence (quick riposte with close def seal)

I vote for +Atk, especially if you're keeping him with his base kit. Owain's speed isn't as important as it seems (depending on the build), especially if you're wanting to deal as much damage as possible with Wrath + Blue Flame, and you don't want him to take too much damage past Wrath's HP threshold, so the defense bane can really hurt. Just my opinion anyway.

I've posted this many times. Owains speed is a trap. On EP he one hits everyone. Build up his def and attack, leave wrath, and let him rip