The Answer of Phantom and Arrow Platter

Ok I was right the first time I spoke LOL. Arrow Platter's turret does indeed activate Armor Piercing and Quiver Cartridge! However, it's sort of weird. In terms of Armor Piercing, it uses the current success rate based on the attacks YOU do, the turret does not stack it. And I feel like it only activates it once per summon but idk. And for Quiver Cartridge, it uses whatever arrowheads you're on atm but it does not 'consume' them. Also, it doesn't activate the FA arrows, only poison or drain. So yeah, if you lock in Drain with Advanced Quiver Cartridge and you have Arrow Platter summoned, you'll always be at full health (except when the boss DRs lol).

Tl;dr: Arrow Platter's summon uses your current 'properties' but doesn't 'stack' them, if you know what I mean. I haven't tried testing with Concentration but I guess it would work the same way.

That's good to know. A week or so ago, I was chatting with a Basiler who also confirmed that the Turret could mysteriously activate Poison and Drain Arrows from Quiver Cartridge.

I do think Turret is like an extension of your character when you use Arrow Blaster, which is why you would indirectly be affected by effects like Damage Reflect when the Turret's hit connects.

Edit: OH, I wanted to ask if you knew what those arrows that appear horizontally of Arrow Blaster and its Turret were. It looks like Phantom Arrows that show up on Arrow Rain, but could it be Armor Piercing or just something irrelevant?