So I've been looking for an answer for this but haven't found one yet,
So currently I'm a level 27 with a nightingale bow and chillrend.
These weapons have special enchants that cannot be disenchanted, depending on what level you do the quest for the bow or childrend will determine how powerful the enchant is.

Getting childrend and the bow at 46 is the highest and that's the best enchant for that, my childrend does 10 points of frost damage I would like to know that if I got to level 46 would the enchant on childrend go to 30points of frost damage or did I have to pick it up at 46 to get 30 points of frost damage.

Thx for your time.

The weapon is locked to the level at which you found it. It will not level up with you once you have obtained it. You would need to be level 46, THEN first obtain the weapon, in order for it to do 30 frost damage. This is true for all "leveled" items in the game.

The one exception I can find is the Sanguine Rose, which does level with the character as far as its effect goes.

I think there are perks in either enchanting or destruction that allows for elematal damage on weapons to become stronger it works with dawnbreaker so it might work with other encganted weapons

The elemental damage perks in destruction will increase the magnitude, but the enchanting perks only apply to newly created weapons.