Athena +spd -res or +atk -res?

I'd probably say +Atk, 38 spd is already pretty good, although if you aren't running high investment and using Wo Dao still, you can get some extra damage from the special if you're faster. If you feel that you're high enough in arena to need 41 speed on an AA unit go for +Spd and some other way to boost damage, if you're looking for a more rounded unit go +Atk. Also, sorry to hear about the bad luck, 7/10 3 stars nowadays is kinda rare.