After a round of final combat using the revolver, is it discarded? The revolver stipulates "cannot be lost or stolen" whereas Cthugha states any weapon is "discarded". Thanks for answering my other questions.

Cthugha's heatwave melts weapons and men as well. I'm not sure of the answer, but I'd say you have to discard it

i'd say the opposite. just as it isn't destroyed/lost in the blizzards (i suppose?) when you don't have to roll for it vs Ithaqua, it somehow doesn't get melted or discarded vs Cthugha..

The issue here is the term "lost," which isn't really used anywhere else (at least to my knowledge). What do you know, inconsistent vocabulary causes rules problems in Arkham. Come to think of it, "stolen" isn't really used as a mechanical term either. Some encounters involve people stealing your stuff, but they always say "discard." I'd say the Deputy's Revolver should be interpreted as saying "This item cannot be discarded against your will."

The "lost and stolen" ability is already pretty weak. But that's not an excuse for my argument. But, anyway...

For the purposes of this ability, "lost" pretty much means "involuntarily lose possession of." This would apply to Ithaqua's SOB ability and Cthugha's attack. Note that for Personal Stories, "lost" includes "give away." This can be concluded when you consider that if this were not the case, and Zoey gives away her Cross, she's now immune to failing her story. This cannot be the designers' intent.

If, on the other hand, you got the Epic Battle card that said "any investigator who wishes to attack must discard a weapon or spell," and you choose such an item, you must discard it, because you've "chosen to allow it."

Unless, of course, it's your only weapon/spell.

Assuming, Walk, you meant the Epic Battle card—

I don't think so: you either choose to discard that weapon and be able to attack, or you opt not to attack this round. Discarding the weapon is the cost to attack this round, like how using Food requires you to discard it. Losing the item is not mandatory (such as if it said, "before attacking this round, each investigator must discard one weapon").

Or maybe I've misunderstood.

Oh...yes, I was referring to the Epic Battle card, but I'm not entirely sure what I was thinking at the time. Mabe I just absentmindedly ignored the "must in order to attack" bit.