Ok I guess I'm missing something I can't tell if thats wear or just how the design is supposed to look.
It's a bit blurry but it doesn't look like wear. Also, these commems are fairly rare in AU; they didn't really circulate (they were made as collectibles and were rarely spent). PCGS has graded more MS 66s than all AU grades combined.
I have several different ones and found them in circulation back in the 50's. They did circulate because after the war if you had 50 cents you most likely spent it. Of course, there were those that did save them, and most of them were held.
Some did circulate but it wasn't common (especially with the low mintage). Something like the 1892 & 1893 Columbian Expo Commem is way more likely to have circulated because the mintage was high and unsold examples were released into circulation. Edit: if we look at the PCGS page that describes the Hudson, the mintage was 10,008 and PCGS estimates 7,750 have survived; of those, 6,550 are estimated to be uncirculated (MS 60 or higer). https://www.pcgs.com/coinfacts/coin/1935-50c-hudson/9312
I suppose I should clarify. I agree that the Hudson's and some other low mintage didn't see much circulation. I did find several such as the BTW and Stone Mountain in circulation. It seemed like BTW's were treated like any other half.
Nice detail on Neptune's face, and decent to very good detail on the sails. This is a notoriously weakly struck commem, and most have weak faces, weak sail detail, or both. This is a nice strike, with good skin and colors that are liked on this coin, but the ding on the obverse has me on the fence between 66 and 66+. If it wasn't for the ding, I'd be at 66+ or 67. Also looks like it's in an older holder, so there's that too. I'm going to play it safe and say 66, with an outside chance it's in an OGH at 65. Nice coin!