Something that I found very striking about TOS is how often there are episodes that feature a good dose of sword play. Indeed, if you watched the right selection of stories in a row, one might be forgiven for misinterpreting TOS as something of a sword and planet type of series. At least, that is a thought that I had when I went through the series on DVD watching episode in a somewhat random order and ran through Day of the Dove, All Our Yesterdays, Bread and Circuses, The Squire of Gothos, in close proximity to each other. You could even squint a little and disregard the fact that they're not using actual swords in, say, Amok Time...I can't remember if the Gamesters of Triskelion had swords or not in the gladiator contests, but same idea there.
If you consider that Sword and Planet is basically meant to be science fiction with the strong appearance of the trappings of fantasy stories, you could probably even look to stories like The Cage/The Menagerie for it's evocative imagery of a castle or fortress, and also consider Catspaw with it's sympathetic "magic" which is explained away as a different type of science. Also, throw in how much the travels of the Enterprise crew take them to worlds that are a much stronger reflection of Earth than they became with later ST series.
Of course, an episode like Day of the Dove challenges the initial label of Sword and Planet, but then I thought that it could have it's own label, exemplified by Day of the Dove: Sword and Space Opera.
Based on what is seen in TOS, Starfleet might very well just mandate swords for defensive combat purposes on landing parties, and it could even have been justified in story by saying that many cultures respect the symbolism of a sword as a more straightforward demonstration of arms than, say, phasers. A more honest type of weapon? The Klingons might have respect for that. And there are plenty of episodes where phasers are rendered useless, so having a sword handy as a back-up might be useful (plus which, plenty of entities are shown to render phasers useless, only to turn around and provide melee weapons).
Anyone get a kick out of all the melee fighting to view ST through this kind of perspective?