Briefly tested Windhose against Yggdrasil Omega with Glorybringer. Here's what I got:
- Awaken: Double Attack and Triple Attack boost to team (see: Xeno Phantom Demon Blade)
- Attack: 25% bonus Wind damage
- Defend: Counter on damage (possibly dodge; a 'miss' text appeared over Djeeta). Damage cap around 400k. 4 energy cost
- Resonance: Instantly fill caster's charge bar. 5t cooldown, 2 energy cost
It's likely that the attack bonus damage rises to 30% or thereabouts like with the 4* uncap. The awaken buff might also rise in power, but I don't have a clear count of how much of a buff it is. Finally, it's worth checking if the Defend skill is dodge-counter (like Ushumgal) or damage-counter.