User blog comment:Zolnir/RWBY Episode 8/General Reviews & Speculations/@comment-4365658-20130907052845/@comment-11188061-20130907163052

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A scar is formed when a wound is healed, but was too deep that it left a mark on the skin's surface.

Following your deduction that she got the scar when she was punched, then the wound should be very fresh with blood bleeding out of it.

You can see very clearly however, that the scar was completely dry and not bleeding - which translates to the fact that it's already formed since a while ago - in the screenshots.

A much simpler explanation of why she didn't have a scar in the first place would be that the punch wiped off the makeup she used to hide the scar. I've said this since a long time ago in the Speculation House.

You called it a scar, people, and you don't even know what scars actually are?

I'm also pretty sure that every student - except Jaune - has monster fighting experience. None of them looked the least fazed by Ursas or Deathstalkers or Nevermores whatsoever. If this was their first time encountering live monsters at least someone would be shaking in their boots, but they did not.