I see a lot of heathens (and non heathens) wearing Thor's hammer around their neck. Does that represent anything in particular? Or is it more similar to a cross or star of David where it's kinda more a general symbol of the faith?
Chiefly, it’s a symbol of protection. Thor is the god who protects Midgard (Earth) and humanity, so wearing his weapon pays a kind of homage to that. It’s also a relatively well-known symbol of the religion as a whole–it’s a recognized emblem of belief by the US military, for example–so it is used by a lot of people to identify themselves as Heathen, as one might wear a cross. Up to this point at least, it has not been commonly appropriated by white supremacists in the way that some runes and other symbols (such as the valknut and sun wheel) have, so it’s a fairly safe identifier.
I can’t really speak to its use by non-Heathens, but I imagine that it’s often a case of people seeing the pendant and being told it’s a symbol of protection, then wearing it without knowledge of the religious context. There are other reasons a non-Heathen might wear one as well, such as an enthusiasm for Viking history, but I imagine that’s the most common explanation.
Thanks for asking, and let me know if you want to know more!