Because in a properly balanced game there are a range of match ups.
I am powerful, wolves, bears, most bandits, etc fall easily.
I am powerful, but some higher level bandits, vampires, etc are equal to me and the fight can go either way sometimes.
I am powerful, but a dragon, a dragon priest, etc can still make me fight for me life and force me to earn every bit of damage against them to win.
That's proper balance.
Well put. That sounds like a proper balance to me.
How about introducing new items. Like for smithing you need a certain kind of oil along with the refined ore or leather to be able to upgrade an armor or weapon, and of course that oil is very very rare random loot, and for each step in upgrade level you need an extra potion, so for legendary you would need 6 of those oils, or howmany steps are there.
Same with enchanting, but instead of oil some kind of crystalpowder next to the soulgem, maybe those soulgemshards you find here and there.
It wouldnt be so evident to make legendaries out of the blue.
the idea for making it purchasable is nice too but at least it should be expensive as hell to do it. As some have pointed out that it doesnt require work to do it, just cash. If that would be the case add a perk to speechcraft, alows for purchasing item upgrades and enchants. Like 80-90 speech required. Make a use of speechcraft in the process aswell, so instead of putting points in smithing or enchanting you have to put em in speech.
Some of that tends to make it near-impossible to upgrade weapons, though. I can understand perhaps the highest level of imporovement - you can justly say that perhaps the term "legendary" should in fact mean "legendary", and perhaps require rare substances to achieve such a level of quality. But not the lower levels of improvement, though.
Also, as for speechcraft, it sounds unlikely to have to convince some master smith to sell you his good stuff. A master smith that can improve weapons to legendary status would be in high demand, would have a valuable skill, and would be looking to sell his products as widely as possible in order to become rich. You shouldn't have to beg for their stuff, they should be wanting to sell it to you - but of course truly legendary-quality items should be very, very expensive.