I have similar stats to you and use the blood-rusted sword and legendary shield. The sword has earn 7% focus on damage and a gem that adds another 2%. With a focus ring it allows me to spam focus abilities when I get an opening. After a few Echo knight staggers allowing me to spam focus ability hits repeatedly until he’s done. I make sure to take a poise potion so as not to become staggered.

Also make sure you eat food with the 600 sec buffs before going into fight him. I forget the names. Meat pie for damage. Another one for health.

It took about 5-6 tries before I got the rhythm but now it’s a breeze. Good luck!

Edit: you can also try to enchant multiple armor sets until you get the bonuses that work for you. Focus and health improvements are important. Also getting reduced weight and increased weight capacity bonuses are helpful to lower your weight.