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Relentless focus (NB skill) and Weapon damage enchantments would be other possibilities for red glowing weapons.
If it's more like orange, it could also be molten weapons (dk skill).
Sometimes spamming certain spells causes overlapping glows, there's something on Templars that makes their weapon glow golden, on certain staves it can be this incredibly bright light bulb following you around, as if you left it in the coals too long.