When i originally read this I ignored it since the learning curve was so steep, seeing it again in societies brings it back...Does this mean that every magi has a free supernatural ability?
You could say that opening the arts remove the previous ability (like an ordeal) to grant the power to use hermetic magic
Since hermetic magic is hermetic I prefer to keep ordeals out of the equation. The loss of the previous ability is because the pater/mater is not competent enough to keep the ability, not a sacrifice in power.
Keep ordeals and other stuff like that to the mystery cults, thank you.
Yes. ArM5, page 36: "The ability to cast Hermetic magic is the single supernatural ability possessed by Hermetic magi in virtue of The Gift". It'd be a bit difficult to be a magus without a supernatural ability, after all.
The basic assumption is that Gifted characters manage to pick something up along the way. Hermetic magi managed to pick up a whole Hermetic apprenticeship, which is a better deal than most. Gifted characters are not born with any particular supernatural abilities; they are born with the ability to learn any particular supernatural ability.