I realize you said HAND brush cutter, but:
I really like my Stihl Kombi with the Power Scythe attachment for brushy areas. The primary reason I bought it was to avoid getting poison ivy. When using a string trimmer it often makes it look like I got into a fight with a salad shooter. Some areas have poison ivy and that doesn't turn out very well. Withe the Power Scythe, the cut material simply falls over and is no problem.
It will cut material the size of my thumb with ease. It isn't a "one trimmer dopes all" tool, but prefers tall, thicker, woody stemmed weeds rather than lawn grass. I tried using it for general trimming but it doesn't do nearly as well as a string trimmer. Once or twice a year I go all along the fence row and around to the different trees in the yard to cut small limbs that rub the tractor cab.
https://www.stihlusa.com/products/multi-task-tools/kombisystem-attachments/fhkm145pwr/