Loz
Mongoose
Except that in higher societies people did attend parties armed, with rapiers, slim swords, sabres etc. depending on time and place. Some have been ceremonial but others have sure been useable by their wearers.
My point is that chosing weapon X might be mechanically superior in combat against weapon Y - but weapon Y might be culturally accepted, whereas X could get you weird glances, reputation as a barbarian etc.
Precisely. Roman Legions used shortswords because they offered a more practical application for their style of fighting than a longer blade. Yet within Rome all weapons were banned. And whilst some no doubt secreted knives around their person, it was largely observed. Society imposed a moral code on its populace. Martial traditions and fighting styles imposed another.
In feudal Japan, entering anyone's house armed was a disgrace (and only the samurai, a social class, had the right to walk around armed). Use of certain weapons was considered uncivilized or marked you as part of a certain social caste. Few samurai would pick-up a naginata (polearm) which was considered the weapon of the sohei and yamabushi (warrior monks). The yari (spear) was the weapon of the lowly footmen of the army. Yet all these weapons offer distinct advantages over a katana in many instances. And, before anyone offers-up the fighting style of katana/wakazashi (swords forming the dai-sho of the samurai) as an example of a culture that mini-maxed with two weapons, it was incredibly rare. The katana was mostly used two-handed with the wakazashi acting as a back-up weapon and not a defensive one.