Mages guild rank 10 is a few hours of running around with an add-on. Undaunted max rank is several weeks of 1-hour-a-day or less. Fighters guild 10 is a few hours of grinding.
Vigor at Assault 10 is a few HUNDRED HOURS of AP farming, and even more than that of casual PVP. That's OK for a PVP-only passive, but for a skill? No. Same goes for the other skills like magicka det. More that 40 hours of PvP is way to much
Much lower rank for the skills, but more good PvP only passive for higher ranks