So I finally found Sapros the Corrupter, which seems to be the most-talked-about melee weapon. It gives significantly less damage than my Sagaris Tartarus - about 15% or so. I swapped it in for a bit and didn't notice myself killing any faster. I thought I noticed it being a bit slower, but that might be mental bias from knowing that the damage is lower.
Is there a particular scenario where it shines? Should I swap it in for boss fights or something?