As it is right now, Riskrunner is so situational that I didn't touch the gun since 3 years (until now to test it again, its still useless compared to other exotics like Trinity Ghoul). Riskrunner would be much more played and useful if it would also trigger its main perk on arc ability kills. Landing an arc ability kill in PvP is still some work and when taking damage from arc weapons you get it anyways (afaik). In PvE not every enemy has arc, so there needs to be a compensation that is not just your arc grenade.