2 quick observations:
a) yes, the +20, +30, +40 damage enchantments on lower levels are way too overpowered. Larian already publicly stated they are over the top and they will tweak it a little bit on the next patch.
Knowing this, if you realy think those enchantments are broke and taking away your fun, i advice turning it to "hard dificulty" or just ditch the weapon with that enchantment, just dont use it for your enjoyment, the game gets more balanced in dificulty witout it.
b) You are still low level

it gets harder later on, with some mobs even of lower level giving you a hard time if you dont play a more defensive "hide & seek" game.
Of course there are always the extremely skilled that come and say that its still too easy, but i honestly feel the game has a good dificulty curve, and you still have the hard mode

I was using dual wielding on my mage, with 2 +40magic damage weapons' enchantments and i was 1 shoting everything. in hard dificulty was OK, but the mobs were also giving me a lot of damage, so i decided to just go with 1hand+shield, with just 1 weapon using +40magic damage, and normal dificulty and it was more balanced. You just have to reach a setting you are confortable with.