Has the Geneva convention ever stopped anyone? They can only arrest you if you lose the war, and people don't tend to plan for that.
Blinding laser weapons are in the same category.
Chemical weapons are incredibly useful, just awful.
https://acoup.blog/2020/03/20/collections-why-dont-we-use-ch...
They're not. They're effective against an unprepared adversary. Any real military will have anti-chemical-weapons tactics and protection.
So this happens: you douse a building with a gas, and then walk inside and get shot by defenders in gas masks. And by the way, you also will have to wear a gas mask yourself.
They're "intended" to cause only temporary blindness
Aside the sci-fi vibe, I could imagine James Bond esque - still quite hard to use, has to aim for the eyes, scatter can cause collateral damage, doesn't work in fog, rain, etc.