"Dude, you crazy?! I've been waiting for you so long I grew roots and then I wanted to leave but I HAD to keep waiting! And I can't even knock myself on the forhead to express how stupid you are because my arm got stuck like that last time I tried to do it!"
When I painted his arm, I was thinking it just had only four fingers (cause you know, branches aren't limited to real anatomy ) and so that's the index finger, but it could be his middle finger if you like the idea better since I haven't defined how many fingers exactly the branch has, it's in the process of fusing and warping and stuff like that at the moment
When he's a tree all this bark stuff really acts as armor, you can't really hurt a tree with, say, an arrow. I imagine him uprooting himself and marching on his roots and the roots can dig through the ground and burst from under people and impale them or trip them or wrap around them so it's a terrible, terrible thing to run from. And in pointy-eared humanoid form he can probably pass through trees like a dryad. And ambush you... and maybe he can command vegetation to hinder your movement.
And a forest full of these guys and gals (probably they have female version too, just for the sake of equal opportunities (or some people's fetishes ), or those are actually real dryads)is a place you don't want to end up in unless you are a famous forest friend.
Hey I know what a Leshy is Though until now I didn't know how exactly it's spelled in the latin alphabet in DnD 3.5 edition for example he was (not quite, but similar, though more like an epic forest elf) spelled leshay. (he was very epic btw, and in their version looked a bit like a drow for some reason, to which I objected but the artist wasn't slavic so...)
And then the tree chopper makes a face that viewers would find cartoonishly funny while to him it's plain horror, and then he probably screams to the viewers' amusement while it's actually pretty horrific. Camera of course doesn't show what happens in order for the viewers to still be amused and not traumatized for the rest of the film.
I actually imagine him uprooting himself and chasing you like a gargantuan tree-centaur/spider/multipede creature and the roots sort of tripping you when you try to run and you fall down and they impale you and then you're dirt and fertilizer. Or they just pin you to the ground while the guy looms over with spiky arm-branch clubs and a psychotic look. Bonus points if random animals start attacking you spontaneously during the whole experience, as well as the whole croud of other rabid trees (or tree-elf-dryad-people)popping out of every tree you run by.
Either that or he simply passes trough trees like a dryad and when you think you lost him he appears behind you and strangles you or something.
Third option is he just shapeshifts into trees and when he gets back to, um, mammal creature, he runs reasonably fast.