Dark Souls 3 - Dragonslayer Armour - Melee+Frostbite Guide (no heal)

This boss is weak to frostbite. It takes 3-6 consecutive hits to trigger the burst damage. Pontiff Knight Great Scythe has a weapon skill that boosts the weapon with frostbite. It is not the best weapon for frostbite strat but has good range and damage.

Boss' best opening for melee punishment is the three hit combo. It starts always by two weapon swings and continues with either weapon or shield smash. Dodge the first swing on any direction you like but immediately after hit the dodge button again so that you avoid the second swing. Try to end up at the boss' left side (your right). If you end up behind, boss might not do the third attack. Before the smash circle the boss and then dodge behind it. Sometimes it is possible to simply avoid the smash by walking around the boss.

The next best opening is the slow AoE lightning smash. Just get behind Armour while it is holding the weapon high. If you managed to not to dodge you have plenty of time to attack.

In phase 2 while the boss is doing the weapon stance calmly wait for the opening. Dodge the coming attack to boss' left side (your right). Otherwise boss behaves like in phase one.

My advice on how to avoid the projectiles fired by the flying dudes: do not worry about them. If you get hit, you will get hit. The main boss is more dangerous and not concentrating on it causes more deaths than the projectiles.

More helpful information at Fextralife wiki: http://darksouls3.wiki.fextralife.com/Dragonslayer+Armour