As a knight myself, my best advice is to buy a Winterblade / Cobra Axe / Resizer
Any Ice damage weapon, because demons take extra 12% damage from Ice.
If you have a druid, ferumbras' Ascendant is the best place to kill demons, since you can easily kill 200/300+ per hunt, depending on your level and skills.
If you are a solo EK, thus cannot hunt at Ferumbras', the best place (in my opinion) would be at Goroma Volcano, where Morgaroth spawns. There you have mostly demons, so you don't rely on a druid, and have a decent amount of them.
Get some fire resist gear and you're ready for it :)
PS: It is also profit