At the start of the Companions questline, you need to fight with Farkas. However, when we go onside, he just says "We don't fight with magic here, *something else here* now come at me!" over and over and over again, along with the sounds he normally makes when he hears a vampire or something like "Huh?" and "What was that?". I have no mods changing ANYTHING to do with the companions.

The character I'm using right now with the glitch is a male Redguard duel-wielding two Imperial swords. I'm not using magic at all.

Have you installed the unofficial Skyrim patch ???

I think Wet and Cold mod has had problems with hand to hand fights and I think the Farkas fight is considered a hand to hand fighting sequence even though weapons are used. I think it is due to the magic cloaks. There is an option to toggle the hand to hand bug.

I think other mods that alter combat might have an issue as well but they have likely put in the fix for the hand to hand bug.