To detect weapon buffs, I use the "COMBAT_TEXT_UPDATE" event. Unfortunately, the return values of GetWeaponEnchantInfo are updated sometime later, so i have to wait a while before calling it. Currently, this waiting is set to half a second, which worked fine for me, but obviously isn't for everyone (probably depending on latency). That's one of the reasons why I (still) would like someone with an american WoW account to ask Slouken in the official forums for an appropriate event when GetWeaponEnchantInfo has been updated.
Anyway, I will tweak the wait time a bit more when I have time.
Seems to be working fine for me atm :) But I agree, it's a very messy workaround.
Weapon enchants do not show until another buff is applied after it. I'm assuming this is because these events aren't fired by SpecialEvents like regular buffs are, as I know I had the exact same problem coding one of my older mobs; the code is hooked before the event, whereas SE-Auras runs afterwards.
Version r35969 shows a stack count of 1 on the Stealth buff icon for the Rogue. Unfortunately I can only Stealth once. :)
Same issue with priest's Touch of Weakness
There is an awful lot of non-stackable buffs that report an application of 1. The Blizzard UI gets round this by hiding the stack count for any buffs with an application under 2 - currently Buffalo2 only hides any under 1, that explains the weird behaviour.