So we have no idea of his abilities, except obviously he summoned a giant worm. He used the Naraka, which is just range over his Thema. His Thema made a giant worm out of nothing, so it's probably Mansuya (because that's the only one that seems to alter reality).
So... a Worm, with the vision and mental combat along with mental images come into reality...
The worm spouts rocks and lava...
All of these things are natural things, and he worships this thing called "mother" which from his profile I can only assume to be mother nature.
Stainless also worships her, but decidedly less than Thresh does. Thresh's whole existance seems to balance and depend on the "mother".
Thresh's very name happens to be about separating things out in a field as a type of farm equipment...
So... I'm gonna say.... Thresh is a
Threshing Machine!
Not only is his name based off of it, but his attacks are decidedly "natural" compaired to everyone else's. His entire existence also seems to depend on mother nature, which... actually.. the reason he was invented was to thresh corn or other plants like that.
*shrugs*
makes sense...
