Well, Jando of the Three Sisters is really broken
Anyway, I know nothing about Blasphemous, so this debate will be a beatiful dialogue.
From what I see, their AP is almost the same, TPO being 0.24 tons and Arthur 0.20, although TPO can increase the damage.
Arthur has ludicrously higher LS, and although neither of them are grapplers, parrying Arthur's weapons will be harder than normal and TPO would be pushed away or thrown off balance while trying to shield himself, although he wouldn't take relevant damage.
I must say I wasn't sure of this myself, given how things work irl, but after asking a calc member, this seems to be the case.
As he usually does in battle, Arthur will attempt to zone TPO out as much as he can can, running and jumping around to prevent him from getting close, all while he throws his weapons.
I'm not sure if talking about skills makes sense, since TPO also went through a similar journey (although it might be said that Arthur had more adventures? idk) and are pretty battle and life-savvy.
I'm not sure how well TPO will do in closing the distance and get into melee with Mea Culpa, as Arthur's whole bread and butter for his entire life is blasting the enemies with various weapons and stuff.
On his own, TPO has handy rosary beads that make him resistant to a good deal of Arthur's esoteric spells, and that's a plus for him.
TPO would also have to rely on his ranged attacks, if he fails to get into CQC. His file says he has limited mana, how does it work? Does it recharged overtime? How many spells can he cast? That could be a plus for Arthur, given that he has basically infinite magic and only needs a few seconds to charge his spells (and can do it while moving and jumping).
Most of both's magicks work better at close range (at least from what I see
here), and while Arthur can fight well even without them, TPO seems to need to rely much on them.
That said, Jando of the Three Sisters
seems an instant win, so if he pulls it out, he wins.
How does Tiento to Your Thorned Hairs work specifically? The in-game description, from what I read, says it protects TPO from all evil. Does it refer to any attempt at harming him, or is it specifically a protection against evil beings and powers? Because if the latter is true, then it might fail to protect him against Arthur.
Take everything I just said with a grain of salt, and this is far from a vote, it's just a first step while we wait for Antoniofer's input.