Unfortunately it hasn’t been working for me, I have tried many a time but doesn’t seem to count as a shatter damage final blow. I’ve used every type of grenade and people are suggesting it only happens from the glacier grenades which makes it near enough impossible to pull off as the damage is minute and the timing has to be perfect. I personally think it’s bugged and has been bugged for ages just slipped under the radar as you can acquire new ones for other playlists. Thanks for the suggestion I will try out and see if it makes any difference!

I don't know what would get the kill, but how about Glacier Grenade with a Wave-Frame Grenade Launcher? Those GLs break the crystals in one hit and do about 130 damage in Crucible, so not enough to get a kill on their own. If you have Dead Messenger, that could conceivably break every crystal from the grenade at once.

That might be the best idea I’ve heard yet, I will be trying this as soon as I’m home! Going to dust off the dead messenger and blast some ice! Thanks for your help, I’ll update you once I’ve tried!