I would think Mandy could just shoot him repeatedly, we haven't seen much of his protective shield, I think one time.
Geralt is faster and could knock him down with TK before getting shot, but he doesn't seem to be capable of targeting a specific object so he couldn't yank the gun away. Unless he can KO Mandy with his TK push...Mandy could just shoot him while on the ground I guess.
__________________ Chicken Boo, what's the matter with you? You don't act like the other chickens do. You wear a disguise to look like human guys, but you're not a man you're a Chicken Boo.
With Mando having far more equipment and Geralt only showing off possibly 2 of his signs, it's heavily in favor of Din.. However, if Geralt hits him with the full force Aard that blasted the Striga 40 feet down a hallway hard enough to bust stone, Mando dies on impact.
In season 2 when he shows all his powers(Force field, flamethrower, stronger tk, mind control, ward that slows you down and hurts you when you step on it, it'll be a far better fight.
https://gifs.com/gif/E85V4l - He'd easily be able to if he used the full force Aard we see. The other times he was clearly holding back because he was fighting people, or like in the games, aiming at multiple targets so the blast was spread out and not concentrated. If that doesn't outright kill him, Mando will be out of commission for a bit.