I do like your theories CanadianBottles.Yeah the crown/blob finish is odd. I have two theories for that - one is that they used a lightning stopper but wanted the option to switch over to crown tops at a later date. The second theory is that people had come to associate that exact form of bottle with Weiss beer, and they wanted to keep it looking as similar as possible when switching closures. This is something you see with those Irish round-bottom ginger ale bottles, which continued having quite rounded bases even after they were made to take crown caps and were able to stand on their own. Since lightning stoppers worked on standard crown top bottles, I'm leaning towards the second theory.
I cannot prove this, but I know that it took special tools for the glass company to make a CROWN TOP lip. The key to the lip finish was it HAD TO BE precise for the cap to fit correctly. In the early day of the CROWN TOP these tools may not have been readily available so the glass company made due. I don't have a photo of it, but I have had beers with what looked like a cork top blob with the crown lip on the top similar to the Willms beer. I know for sure there are HARTMANN & FEHRENBACH bottles floating around that have this oddity.