Dark Knight always fired off beams of purple energy out of their weapons. This dates back to FFIV. It's also been a feature of the job since it was released in Heavensward. Because nostalgia.
I'm baffled at the number of people who want me to remember things that never happened. There was someone in the healer forums earlier going on about the things Healers had to do during their week one clears of Gordias. A raid that took over a month for the first clear to happen. I know everyone wants to fit in, but it's incredibly simple for anyone to check if you were actually around back then. And to be honest, it doesn't really matter when you started playing at the end of the day. It doesn't add any weight to your opinions.
I remember Scourge. But what was it that you liked about it? I'll accept that it looked cool. But what did you like about it from a gameplay standpoint? The fact that it reset your combo? The fact that it was a standalone DoT that most people struggled to break 80% uptime on? The fact that it was 500 potency, and was replaced by Bloodspiller, which was also around 500 potency at the time? I remember Delirium. All three completely different iterations of it. Again, the first one did look cool, and was well designed in the context of the Dark Arts system that existed at the time. The INT down buff was gamechanging, and it was hilarious to see influential naysayers in early Heavensward who claimed that DRK would never be meta eat their words on the first raid tier itself. Stormblood had the worst iteration of Delirium, being both ineffective and contributing to the MP overflow problem that we had at the time. Hopefully they'll just pick a concept and stick with it. Power Slash? I don't remember Power Slash, and you don't either. Nobody used it outside of gpose.
5.0 didn't remove the 'branching combo'. If you want to argue combo pruning, then 4.0 did that. In 4.0, we lost Delirium as a combo step. But your enmity combo? Who cares? Everyone lost their enmity combo after Stormblood because they weren't being used.
I know everyone wants to jump on to the forums and just react to the info dump that they've just received, and that's fine. If you want to critically assess current issues in job design and more importantly raid design in the context of the proposed changes, then even better. But I don't understand why there are so many people posting this nonsense about 'remember Heavensward' when they very clearly don't remember it themselves.