Can you list out what mods you installed? Someone here may have solved a similar problem with one.

Otherwise you may be better of going to Nexus and looking on the comment pages for those mods to see if you can find any clues, or asking on those mod comment pages.

One thing you might try first is uninstalling the mods completely, delete your config file & re-verify your Valheim installation through Steam... and then reinstalling the mods one by one and firing the game up in-between each mod install and testing your combat & stuff for a few minutes. That way you may at least be able to figure out which mod is causing the problem so you can look specifically at that Nexus page. And sometimes just doing that fixes issues like this.

Hope you find a solution, that sounds really frustrating

Valheim plus
Plant Everything
All Tameable
Atach Armors
Beasts of Burden
Better UI
Blacksmith Tools
Chaos Armor
Character editor
configuration manager
custom textures
epicloot
equipment and quickslots
Farm Grid
Frostmourne
invis helmet
Nexus update
remember ip
runeswords
smart containers
TP Wolfes
More two handers
Windlass

Hmmm... just looking at that list I'd suggest uninstalling the armor & weapon mods first, re-verify the game through Steam, and try your combat again.

If that works, then add the mods you removed back one at a time & test in between each addition to see if you can find the one that's borking your attack animation up.

If not, you may want to put the time into doing the more drastic suggestion I had and trying that process again but with ALL the mods.

But! Hopefully in the meantime someone else has some other more specific advice for you to try.

Good luck!

I will try it thanks