During my 3 Beta runs I noticed that there seems to be a great discrepancy in some mob's shown lvl. Massive undercons like a LVL 7 Skelly that alone can make life difficult for a lvl 16 and with more than one just ends your life. The levels shown need to properly match up with the mobs or they need to be listed as group or raid mobs in some manner so people don't get their ass kicked by something they thought would be a pushover.

Hell in PVP everything is LVL 50 but people in the teens can take them out, but that may be another case as I think PVP may be level scaled.

Those enemies that you mention are probably the "elite" mobs, meant for little groups to defeat them, they are intentionally so hard to defeat. Also, they have a slightly different health bar in the HUD, which indicates their "elite" status.

Those were mobs that are supposed to be really hard, like elites.

In PvP everything is level 50 and characters lower than that are boosted