Have the amount of experience points been changed(for hero level)?
Hey,
indirectly yes. I think you are relating to the XP bonus for winning the last Guild Wars fight. This one isn’t lasting for 3 weeks anymore, since it was always a bug. This one is fixed now 
So in future this bonus will last for only 1 day after the won fight.
Or, arena doesnt give hero class xp anymore.
Yeah the one bug which didn’t need fixing… 