Threadlings have always been a favorite part of destiny for me. I love the brood mother vibe, the whole we are many and you are few feel. But swarmers fundamentally doesn't really have a use. There is 2 cases in which you would use it, On pure strand, or on Prismatic. Both of which have access to Arcane Needle, Which unravels. Once enemies are unravelled you don't need to keep applying the debuff as it spreads passively on damage and since you get it from Your melee, Swarmers feels like a waste. The other part of it, 2 threadlings spawn from a tangle, Sounds cool but. Weavers call + devour on prismatic and Pure strand having generation etc, feels like you don't really need more niche ways to make more of them. Giving Swarmers / Spirit of the Swarm a bit more, like Sever on Threadlings or Horde Shuttle innately would make it feel much nicer to use in higher end content. I feel like the damage is honestly fine for Threadlings, they just need a bit of Utility for the Threadlings themselves. Arc grenade jolt, void weaken, Stasis freeze, Solar scorch/ignite. But Threadlings just damage and giving them an Exotic to give them some Utility doesn't feel good.