Just prior to sending multiple slashes of mana made from the sword element, and manifested dozens of blades before launching them directly at Milo, the undead had extended the circle created through his unique battle art, stretching it right over the living to prevent him from defending himself with any energy whatsoever, in essence, Milo had just received the full brunt of the damage with his mundane body.
A body far more powerful than normal, but that was still plenty vulnerable to energy-based attacks.
The corpse almost found it too easy, striking at targets that could literally not defend themselves guaranteed that severe damage would occur, and as long as he maintained his art, they wouldn't have access to regeneration either, unless they somehow had a naturally high healing factor that is.
Stripped down of his magical capabilities however, Milo was just a human.
'That did not kill him' the cadaver would be able to tell if his attack had slain his target, he could sense that many blades of grass had been annihilated and deprived of life force, a few insects crawling within the earth as well, but that was it, Milo was still alive, in fact…
'Why does it feel like I didn't even hit him?' directed his sabre forward, the headhunter's senses were spread wide, an advantage of having no head, like some types of dullahan, was that he actually possessed a vision of three-hundred and sixty degrees, in fact, it might even be better than this as he did not even have blind spots above, or directly behind his head, for he had none to begin with, the empty space above his shoulders was like a colony of eyes that were not physically present, and thus, did not get in the way of each other, apart from hiding behind his own body or solid objects, nothing could hide from his sight, not to mention the benefits of having access to undead synesthesia, which melded all senses together.
The perception of the dead was incredible to begin with, even the least perceptive of the undeads of the empire were incredibly aware of what happened around them, but headless headhunters in particular possessed incredible senses.
So he did not doubt that Milo was still where he had been standing moments ago, or at least, that was still within the cloud of dirt particles that had been risen.
'How come I can sense him through my battle art?' this was the real question to bothered the corpse, and the answer came in the form of a bright radiance, shining like a golden star in the darkest of night, the actual night had yet to come over the Emerald Realm, but the great glow was so overpowering, that all other source of light might as well not exist, as they seemed just as dim as darkness in comparison.
The dirt cleared, and the shine went down, revealing a completely unharmed Milo.
The headless slightly lowered his sabre.
"You've gotten far stronger- Stronger than I had been told in fact… Did you make a breakthrough of some sort since your intrusion upon the underground?"
Milo did not respond, he was still standing right upon the stretched-out circle of the battle art, but he could not be sensed or suppressed nonetheless, the golden mana simply, and unequivocally overpowered the art, there wasn't even a struggle, which was why the undead didn't notice anything.
"Well, it doesn't matter" raising his blade again, channelling mana directly into the weapon, he lunged forward at the same time as the living did, both seemingly passing right by one another without any resistance, a cut manifested across Milo's chest, but not blood was drawn even after several seconds passed, only his shirt had been harmed.
On the other hand, the undead seemed just as fine at first, but quickly after, a gaping hole was punched right through his chest, dust flowing out of the wound, gold permeating it all, but curiously, the powerful, brilliant mana soon faded away.
"Mmh… Not bad, you used to always lose when we did this during practice before…" mumbling to himself, the headhunter turned around and dispelled his weapon as the hole in his chest slowly mended itself.
"I suppose trying to convince you is no longer achievable, so let us see one another on the battlefield next time"
"I don't remember allowing you to leave" Milo flashed forth, and went right through where the undead had been standing moments ago, but instead blasting through the undead and making him blow up into a cloud of dust, the corpse claiming Griar's name had already faded away and totally vanished, the mist that had covered the area also went away and it was like nothing had happened as the realm used spirit life to repair the damage done to the environment.
Milo looked down, a piece of white fabric crushed in the palm of his hand, just a little faster, and maybe, just maybe- He could have caught him.
'Griar… Never… I never would have thought that you of all people, would end up …' for a few seconds, as he stepped back into the embrace and safety of the barrier, Milo felt the wrath and contempt he held for the dead surge forward with new life, feeling compelled to take immediate action, but he buried it, there was no point in acting alone and without warning, although what had happened to Griar was awful, the man he once knew was dead, in the true sense of the word, he was simply gone, what was piloting this corpse was not him.
Nothing but a pale imitation of the proud noble scion that he used to know.
Sighing deeply, Milo finished his patrol and came back home, thankfully, he had Helena and although hesitant at first, he ended up telling her what happened.
It was good to have someone he could confide in, although he knew many people, and had many friends, he wasn't certain if he could really bring himself to share that Griar had not only been turned into an undead, but into a demented follower too.
Everyone who knew Griar felt that the first option was likely, perhaps even obvious, but none would like to have it be confirmed, for as long as it didn't happen, there was still a chance...
When Milo heard the headhunter speak, it felt like a stranger was just puppeteering his friend's corpse, that's what it meant to be turned into an undead, to be turned into a warped version of yourself, the ultimate desecration of what you were.
One way or another, Milo had to somehow put Griar out of his misery.