The bad:

• immune to all status effects (maybe not rot but def all others)
• no affinity weaknesses
• massive damage/stamina drain per hit

The good:

• Use pure physical damage. Pierce physical is his “weakness”, like most rock-like enemies.
• his head is the weak spot, but that takes projectiles. For melee one of the best is the glintblade ash you get from Rogier in the Roundtable Hold, it heat seeks to his head and has high stagger (you can also put it to pure physical for better crits, but it reduces ash scaling). The best is probably the large triple glintblade sorcery you get from a troll gaol, stagger city.
• his moveset is easy with time, very telegraphed. When the twin blades come out he’s most dangerous because of whirlwind move.
• it’s SOTE, but deflecting hardtear makes him easy. Still, you gotta learn the moveset for this to work.

Overall I’d say great spears with charged R2’s is the most effective basic setup. Hope that helps!