Got a vice and a thin cut off wheel on a grinder? Or a good quality hard file like a nicholson single cut draw file. You can get them razor sharp with very little work with a Good file.
I have a nasty looking carbide tipped circular saw blade on my big old Homelite whacker. The carbide tipped blades work awesome but beware of the tips flying off if you hit something hard like a rock.
Blades like these work really good if you modify your blade adapter so they fit tight. You can get smaller or larger ones with the same hole size.
I bet this one would rip up some buckthorn or anything else in it's way.