I wish I could give you a better answer. I just bought this attachment but I am hesitant to use it with my trimmer struggling to stay running/possible vibration. I did install the handle and run it for a quick second though. Knowing only that, I can't see why it wouldn't work for brambles or wild raspberry. So long as it fits your trimmer model, it should absolutely walk through that stuff. I would be cautious if you're talking thick diameter type stuff. By weeds, I am not sure what you mean. If a line trimmer will do it, this might be overkill. If a line trimmer would struggle, this should be great. My one apprehension is using it near anything you don't want to destroy...like a foundation or shed until I know how it responds in working conditions. Again, most of that is because my trimmer seems to have an issue right now.

First on my Cub Cadet, the string drum comes off and the brush blade then attached directly to the bolt, with a washer and a nut.

With the Cub Cadet, this things works great. It cuts through small brush up to nearly 1" in diameter, IF DONE SLOWLY. It takes care of all large weeds, (The 5' kind) and the clumps of grass you will run into.

CAUTION: A brush blade on a string trimmer is one of he most dangerous items you use in your yard. Since it will cut an 1" diameter small tree, I am sure it would do qutie a lot of damage to the soft tissue on a leg.

BE CAREFUL and make sure you are on good footing when you are using it. Especially on slopes or other places where you could slip and end up tangled with the cutting head.