Alternatives:
Viral slash (the one on screen): works up til level cap, aptitude can be swapped for [Serration] if prefered, especially if you are doing low level stuff, it can also be replaced with [Hunter Munitions] (only if you got maxed primary arcanes). Tox and cold are left at R1 to keep the slash weight high enough, you can unrank them more to get the optimal weight for level cap(at least 2/1). Consider that aptitude also adds status chance, which will boost slash further. The exilus can be replaced for vig supplies to help with the burst fire ammo economy. If you change the exilus, you can replace the arcane for deadhead to help with the recoil. About the weapons passive (reload speed on headshot kill), it is easy to trigger on low level content, but really hard to trigger over level 1k, as the passive only activates if the bolt kills the enemy with its raw damage, it doesnt account for slash DOT, thats one of the reasons why merciless is used, to boost the reload speed

Corpus (raw tox): swap [Rime Rounds] for 90 tox, max [Malignant Force], swap the bane for corpus and galv apt for [Serration] if not using a primer, as the tox weight will be way too high to use aptitude

Raw slash: swap [Rime Rounds] for [Hammer Shot], apt for [Serration] if not using a primer and [Malignant Force] for [Hunter Munitions]