i haven't come across such enchantment, or it doesn't exist at all?

No, just like there is no fortify alchemy potion, it would allow an infinite recursive loop.

edit: of course there is still self reinforcement possible between enchantment and alchemy but it has diminishing returns pretty quickly. There is a bug/exploit with fortify restoration potions that can be near infinite though.

No near about it, it is infinite.

It isn't infinite, not through the theoretical part, but the practical one. Once the numbers go too high, the game will switch the numbers into a negative.

No, not for me on PC??? I have tested that for a whole Level (72 to 73). There is still nothing negative. Nothing written in red, still the same total, and still the same strength towards Shadowmaster Falmers, Death Lord and Death Overlord, and also all kind of spells...

Once the number got too high, it just crashed my game. In any case, with that exploit you can make any overpowered enchantment you can think of, regardless of whether or not it is infinite theoretically.

Right. Just be sure not to exagerate. Making a lot of tests before helps. A potion of Fortify Carry Weight of 11.177 will give you only 1.162. But 1162 is a lot. When you drink a fort. restoration and then a fortify enchanting at the altar, your enchanted item will look very strong but later, after the effect of the restoration potion is over it turns lower but still with high value. My ring increases my health by 5920 pts as well as my magicka. Even nothing shows in negative but the value is lower, it should turn around 1000 because I can see that my Magicka doesn't move much. Before restarting a new game I'll make more tests on it.

Remember those +100 intelligence potions you could make in Morrowind? And you could use those before enchanting...... or making more intellegence potions?

That reminds me of the comment in Mass Effect 2 of Shepard's "Remember the old days when you could just slap omnigel on everything?" Liara replied "That was a security upgrade that made a lot of people upset."

I could go also high just by switching between enchanting (making rings, helmets, ... to fortify alchemy) and alchemy (to create potion to fortify enchanting)
okej, i did not testid it myabe untill the limits, because i runed out if grand soulgems, and i did not started over again when i found others.

but well, with my enchanted gloves to fortify smitting, and the potion to fortify smitting, I can make realy nice weapons at least

Yes, but with the fortify resoration potion glitch, you can make weapons that do billions of damage. With just alchemy/enchanting/fortify smithing, you can do much, much less. Still a lot for sure, but nowhere even close to the potions glitch.

And don't forget that you can enchant 4 pieces (armor, gauntlets, necklace and ring) for smithing.

Yeeeeah.... Nice memories. I can hardly wait to restart Morrowind. I like Skyrim but Morrowind is the best for me.

I was only doing the exploit for testing purposes and curiosity. I do not play with said exploits and do not plan to do so in the future. In any case, I'm aware of the intricacies of said exploit but was merely painting a picture to how ridiculously high the numbers can get.

Yes I understand your feelings but to test it I have to use it. I mean to play with it. As I said I'm at Level 73 now and instead starting a new game I want to see how it goes at late levels when there are tough opponents and also I want to visit all caves, dens, dungeons, making my own map as I did for Morrowind and Oblivion. But I will still use it in my future games in a different way. I'll go a little more up to the max. level in normal enchanting and alchimy crafting. No exageration... Instead of my 74% fort. health and magicka I'll double it to put it on one item and use the second item for another enchantment. As I had all perks in Alchemy, Smithing and Enchanting I was pretty strong enough. I remain with my glass armor...