I've got a trimmer mower, have used it a lot. It's real good on dry ground - not so good in the mud. The skinny tires have a tendency to sink hub deep, it gets hard to move then ;-)
I use some broad leaf weed killers on the lawn areas. The wet areas are a totally different story, I want the marsh grass, duck weed, thorny-vines, poison vines, saplings, everything dead & gone. FWIW I just spent the last 6 hours weed eating just the drainage ditch along the road. That did not include around the pond, along the creek, the flooded areas, etc. And it'll need it again in 3 weeks at most. I want that *expletive deleted*it gone dead!
And I agree completely that spraying acid would be something to think about 3 or 4 times before touching the bottle - and then decide to put the bottle down. Airborne/atomized acid just sounds nasty.
Reminds me of the time I used a chainsaw to cut some century cactus. It's not a hard acid, but the juices are somewhat acidic, and I breathed in a lot of it. The next couple days were unpleasant, to say the least.
ETA emphasis to making it go away.