Blackbrit,
I've posted my weed fighting setups previously...
#1055 is my weed/brush blade on a Seymour #9 alum. Snath. The blade was new old stock and very affordable, I think 10 or 12 dollars(?). The snath was around $40. Baryonyx carries the slightly lighter #8 snath that would probably be even better. This makes a nice tool for bigger stuff.
#1042 is an outfit I made for my son. I borrow it a lot for light weeds in paddocks, such as where tender ragweed or the like is taking over a patch, but mowing would set back the good grass too much. I swing it just like my "American" snaths, as I think the geometry is more or less the same. I use it mostly out of curiosity as to how it will hold up. I think there is under $15 in the whole setup. The hybrid blade is awesome for a wide range of stuff.
I prefer any scythe over a weed eater! The better you get with scythes, the less you will need or want the trimmer for much of anything, esp for field work! I can do most everything with a light 32" blade I cut hay with, but I like having at least one setup dedicated to weeds/light brush because the setup is different, plus it is good to have a tougher setup so you don't ruin your hay setup.