Was doing some spell research for paladin stuns today and came upon this about enchanters:
http://lucy.allakhazam.com/spellhist...92&source=Live
2002-09-04 11:33 Changed Slot 1 from "Mesmerize(2/56)" to "Mesmerize(2/55)"
2002-07-24 09:28 Changed Slot 1 from "Mesmerize(2)" to "Mesmerize(2/56)"
Mesmerize and other Mez effects may have worked on higher level mobs at the time, especially with the evidence provided within this thread.
Also, I believe a change to stuns was around 6-11-2003 that made most stuns ineffective against ALL NPCs above level 55:
http://lucy.allakhazam.com/spellhist...16&source=Live
2003-06-11 11:12 Changed Slot 1 from "Stun(4.00 sec)" to "Stun(4.00 sec/55)"
Artelius Lightweaver 60 PAL <Auld Lang Syne>