How we know both assassins were actually under-level:
- Noob assassin picks unsteady, loud terrain that gives away her position. That's amateur.
- Wearing Bloodfang set hood: another indication of being low-level scrubs.
- Being followed by a warrior. Low level stealthed creatures are easier to spot, which Saurfang does in every instance.
- Trying to hit higher level targets often results in a large percentage of missed attacks(attacking thrall) or no damage(attacking Saurfang).
- Getting hit by higher level targets often results in taking more damage. Both assassins die in one hit.
- - - Updated - - -
Saurfang followed the assassins to Thrall. Implying that they weren't there until recently. If the assassins were on stakeout, how would Saurfang follow them? They'd have been there for quite some time.