The Hunter Exotic Calibans Hand makes the Aspect "Knock ´em down"´s last line of abilities not work anymore. Throwing Knife kills while radiant should return back melee energy. If you have the proximity knife equipped both parts of the knife (impact + explosion) return the melee energy on kill.
If you have Caliban´s Hand equipped this does not work anymore and you will loose your melee energy completely.
The other problem is that in the exotic perk description it says: "[...] ignites the target on direct hit", which it clearly does not. It only seems to apply scorch.
This makes this exotic way worse than Young Ahamkhara´s Spine and it´s a shame
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It does still work but it's inconsistent as hell. I think you have to entirely kill the target with the throwing knife damage only, the explosion no longer plays any part in the math, if you kill them instantly with just the dagger, you get it back, but not with the proximity explosion. I'm not sure if this is "working as intended" or just a bug though. It's hard to know with Bungie.