I noticed that if you are wielding 2 weapons that sigils won’t stack, meaning if I have a dagger with Bloodlust in my MH and a dagger with corruption in my OH I will only get a bloodlust after the kill and not corruption. Perhaps this was intentional but also if i reverse it and put the dagger with corruption in my MH and move the dagger with bloodlust sigil to my OH I will still only get Bloodlust after the kill and only Bloodlust will continue to stack.
I tried it by clearing my modifiers and moving bloodlust to my OH, but I was still gaining bloodlust instead of corruption.