If there's such a correlation, it's more likely to be indirect, with large urban areas being less religious, and the same large urban areas being likely to be sited next to a river or coast.

As a direct example, the province of Zeeland is often considered to be part of the Dutch bible belt, and it doesn't get much more coastal than that. It does lack a major city.

You're not naked until you're naked and wearing high heels. This is a unisex rule.

And because somebody inevitably has to: https://xkcd.com/538/

Your assumptions make a questionable shortcut. The spear was the weapon of choice not solely because it was cheaper to produce - it was also flat-out better in a wide variety of circumstances.

The cost difference between a spear and a short sword do not have to be very significant for the spear to become the de facto primary weapon.