I've seen others say this as well and after looking at Zephyr Strike again, it looks like this might be a bit too powerful.
I immediately wanted to compare this to Haste which has the following:
- +2 AC
- Double move speed
- Extra action (limited) per turn
Now Zephyr Strike we have:
- No attacks of opportunity against you
- Advantage on first attack per round
- +30 ft move speed
This is really powerful, and considering that most races have a 30ft move speed, adding +30 to that is essentially doubling it. Even better than doubling for small races and Dwarves. Zephyr strike seems like it might have a better home as a 2nd level spell, it might even be powerful enough for a 3rd level spell.
Also, looking at Virtue, there aren't any rules for when you reach 5th, 11th, 17th levels. I'm thinking that +1d4 at each of those thresholds seems appropriate.