"However, it's not clear to me how a devoted worshipper of a god of warriors (e.g. Destor the Adventurer) would show his devotion in-game any differently from a mundane sword-swinger."
There isn't any such thing as a "mundane sword-swinger" in Heortling society*. If your occupation is warrior then there's a fair chance you'll be a member of Orlanth Adventurous (including Vinga), Humakt, Elmal, Babeestor Gor, the Storm Bull or one of the other Gods that encourage that type of thing.
A full time warrior is likely to be a devotee or initiate of a warrior god - anything else doesn't make a lot of sense in terms of the society they live in.
Cheers,
Ash
*Within the caveats of what's normal in that society.
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