An American scythe would probably do well for those conditions, honestly. They're still a fairly light tool overall but their heavier blade will carry them through dense grasses smoother than a lighter one would and American grass blades, provided the heel is as wide as the stalks you're cutting, are durable enough to cut brambles as long as you're nimble enough to guide the blade amongst them. I've cleared raspberry thickets using a 26" grass blade with a glassy-hard edge and it handled the work well. Either style will get the job done, and I've already mentioned my personal preferences, so don't think Euros can't handle the work or anything. Botan at 1SR would be able to pick out a Euro rig of appropriate build for those tasks.
