I think the rock saw blade would be a pain. Rolling, bracing, propping it up, and that's a really small windmill blade he's working on. It would be a job with a bigger blade, and I could see it pinching the blade pretty easy.
I'm thinking along the lines of the shear/ gilloutine idea, but with hydraulic power, built on a semi trailer like the car crushers. Load and push the windmill blade into it with a loader that has a grapple on it. Feed in 10-15' foot at a time, and bam. Big enough frame that the whole end of the blade fits into it 12' x 12' square opening or so.
Something like a overgrown log splitter/ blade and anvil/ car crusher semi trailer monstrosity. Big powerfull ram. Maybe in two halves on the trailer and the press frame unfolds and pins in to feed the blades through. Build it out of some old factory heavy flywheel press.
I'd reinvent the wheel if someone hadn't already made it.