I came here when looking up the definition of “chad”

He got the queen good ngl

I do think it's either Alfred or Logarius but I don't think Alfred's quest line is a requirement. This summon is available to me and I never even talked to him with this character.

Ardeo. Not Aerdo.

This is an Actual NPC Wth?

Seeing as how the Messengers are a reference to the Stand Metallica in Jojo, I refuse to believe this character's not a Jojo reference.

A big wheel?
A big cannon?
A cone shaped helmet?

He IS a living Ludwig's Rifle.

Gunpowder, pyramid

Dynamite with a giant wheel

Guaranteed to blow your mind

Think this is probably alfred if you get him after completing the questline, he is an executioner and his called queen killer. (Spoilers>) even though alfred is dead after his questline, we know that dead hunters can be summoned e.g. henryk.