Limit health loss to 50%
Connor must fight Haytham Kenway and in his present condition, things do not look the best. To beat Kenway, you need to lure him naerby the barrels, stacks of wood, tables or anything that Connor can slam him into. Smash him into 3 objects and the scene will move forward. Counter as much as you can to get the opportunity you need to defeat him.;
At the end of it, just hit the prompted button quickly to end the sequence before you lose too much life.