Game Mechanics: "Blue" on the pvp server

[Softcore PK]

And sometimes higher level players are yellow for no reason.

[Silikten]

I have also ran into people who can attack me, but I can't attack them. How is that correct in any way possible?

[Aesop]

I noticed something funky going on as well. I was able to backstab a druid but was "protected" when he tried to retaliate - then in another zone I zoned in and was automatically in range to level 2's for no reason.