A rapier was a civilian's dueling weapon, not a weapon of war. If the same per-
son would have gone to war he would have used a soldier's weapon, perhaps a
claymore in the case of a Scottish clansman. However, to wear a soldier's hea-
vy weapon in everyday use with civilian clothes would have been very uncom-
fortable and would have been seen as very barbaric.
For example, perhaps the most famous rapier duelists of world literature are
the French musketeers. However, their rapiers were dueling weapons, their
weapons of war were - as their name says - their muskets, they did not use
rapiers on the battlefield.
To give a fictional modern equivalent, you could appear in polite society with a
pistol in a shoulder holster, but if you enter the room with an assault rifle the
society will rapidly cease to be polite.