Windshield has to come out, also the wiper assembly. The offending rust cut out and a new patch welded in. Then good epoxy putty,prime paint under coat. It looks too bad to just patch with fiberglass, and of course a new windshield. You can save a small amount of money taking the windshield and wipers out, but unless you have a torch or mig,it's off to a body shop. If you're lucky, including windshield, maybe $500 +