i just want the duelist helm for a rl30 strength build fashion and i'm being gatekept from leyndell by this dude with his lingering hitboxes straight out of dark souls 2

Never attack more than once in a row, and try to roll/sprint to his shield side whenever you can. His shield hits just as hard as his weapon, but he doesn't combo it as fast or long.

Perfect example of the **** boss design this game has. Combos that never stop, godlike tracking and input reading if you try to even think about healing.

For anyone using the jar cannon with the Arrow's Reach talisman, you could snipe him from the Dragon Temple Altar ledge with the banished knight looking towards the bridge. Just gotta make sure you dodge his fireball and lightning attacks when he notices you, he only performs these once per aggro.

Flame of the Redmanes stagger him quite well. After that I threw rocks at his face once he hit second phase.

The one in Farum Azula seems to be immune to scarlet rot.

pulley crossbow, rotbone bolt, 3 or 4 bursts, 5 at most depending distance proc scarlet roc, retreat enough to lose aggro, but keep an eye on him, watch his health fade away, rinse and repeat
incredibly cheesy, but he DEMANDS to be when he spams homing fireballs at distance, to both heal punish, and destroy you, or face lighting AoE and/or stunlock strikes when in melee

Rock sling and some luck got me through the fight with the Crumbling Farum Azula sentinel.

Give me your armor, weapons and steed.
...A couple of seconds later. You can have your hammer back.

I have tried different tactics, but the one that was by far the easiest for me was an STR build. Level 100, 25 Vigor, 27 Endurance, 74 Strength. A Heavy Brick Hammer+25 with Wild Strikes. Went close, engaged Wild Strikes, and saw his life melt rather quickly. Also, Ritual Sword Talisman.