My guild is 12/16H and we still wipe on zorlok (as an example) every week multiple times. People die from rings, people die from RNG convert, we had the echo cast song, we had someone not notice a green orb, we had a convert broken too late and in the middle of rings. These heroic fights these days have a lot more going on than previous tiers. Hell I watched Blood Legion and they still, too, wipe on bosses.
As a raid leader, the best thing I can say is have some patience, but know when to call people out.
You need to understand every fight from a developer's point of view. Understand timers, understand mechanics, and then figure out player behaviour. Know when to call for a stop to dps to let a timer expire. Taking your fight, Blade lord, I always alert people 5 seconds before the vortex and 5 seconds before the unseen. I always mention to be close enough but not too close, so they don't get stunned. I always mention for paladins to BOP. I always tell people to check your range 8 yards after every single ability. I call out frequently to "use healthstones if you're low". Then I direct the raid to use health stones at the start of p2 and direct healers to use their abilities at certain points. I tell the raid to move to the other side at 12% and the tanks to stay.
And if people still just can't get it, you need to find a new guild or you need to find new players. Some people just have a hard time learning.
So, we had our talk yesterday. We spent about 15 minutes of our raid time for it. I asked everybody what their aims are and how they are thinking to reach them.
Overall it went pretty well. Not only because everybody now understands the others better. What they want and where their motiviation comes from. Addtionaly everybody felt "heard", which I think is very important. I also announced a stratetic concept until 5.2 (Which bosses, which ids, raidtime etc.) and everybody was quite happy with that.
The raid afterwards went really good. We cleared ToE, and did 4 heroics.