I guess, though magic is way he has so many abilities and everyone who don't have anti-magic abilities would be considered trash in the age of myth, hence why he can speak to other ppl from then and them not be affected.
His words can cause fear or compulsion.
Anyway his magic aura paralyzes ppl, causes fear, can cause anyone he looks at to sleep, nulls anything he sees, illusions, his heart beat can kill ppl etc.
It's his none lethal stuff that's gonna have to be used here cause of Naraku's regen.
The WN has like 500+ chapters and 54 are out now so a lot is left. If Arnos is already this absurd, can't imagine how powerful he gets later, or maybe he stays the same since he was op from the beginning, who knows.