Is there anything in the vanilla game that can hold such a huge enchantment?
Anything can hold a huge enchantment "charge", the item limitation is on the amount of charge that can be released
per use (for non-constant effects). The bigger the initial "charge" the more uses you get. That's why the enchant info on UESP says don't waste Vivec/Almalexia souls on CE, you want them as big "charges" on massive per-use items (like Ebony Staff for weapons damage, exquisite clothing for other effects, etc.) to allow more frequent use.
@ Alaisiagae - re our PM convo, I already found these discrepancies A LOT when looking through the enchanted weapon lists. For some reason different weapons in the same "family" (eg. the Shardslayer/Viperslayer/Flameslayer groups) often have different enchant numbers. So you might have one with 300/30 (300 "charge", 30 per use, for 10 uses) and the next listed with 500/50. The effective number of uses is the same, so there's no in-game difference, but the initial charge is impossible under game rules. It's another of the things that need normalising badly in those awfully screwed-up lists...
The unique weapons aren't any better. http://www.uesp.net/wiki/Morrowind:Unique_Weapons - the Black Hands Dagger has a 2550 enchant "charge" (they obviously calculated the 255 per-use cost somehow and multiplied it by the number of charges they wanted, without thinking through the consequences) and Trebonius' Staff has 6500, just so it can get 100 65-point charges. :rolleyes:
I suppose in the spirit of fantasy we could suppose that the original enchanters had access to supreme non-game unique souls better than gods'... I'd just as soon slash a zero off the "charge" numbers and get still very effective weapons. I use the Black Hands Dagger as my short blade weapon of preference, and what I notice is that the huge enchant value means that it recovers charge apparently slowly at the standard trickle rate. But rather than having ten uses per full charge, I'd be fairly happy with one or two charges that I have to hoard carefully, since one hit wth that kills most things, if it needed to be normalised down to a "standard" soul size. That sort of magicka cutback is broadly compatible wth the balance changes hrnchamd is making in the MCP too (4 second cooldown between per-use items).