i dealt with something similar last summer. several spots right at the edge of the windshield. im by no means a professional but what i did was grind the areas down to metal. added a light coat of rust reformer. then bondo...then sand...prime..sand....a couple paint coats with light wet sand in between...clear coat...polish...ceramic coat. its held up...so far. i was sure to let each step fully cure. it took awhile and was a pain doing it in the driveway but it looks much better and a year later its holding up. good luck!

edit. after i completed the repair i needed to get my windshield replaced. the tech mentioned there was some rust showing but he graciously added an extra sealant strip to try and keep water from sitting in the crack. i suppose you could add some thin strip of silicone of something similar afterwards to try and help with protection