The absolute last thing I want to see in a DnD game is creative choices making way for historical accuracy. Unless you are playing a campaign that has been tailor made to take place in a historical period, but that's obviously not the case here.
DnD, and in this case FR, is about the larger than life elements of story telling and roleplay, and about transporting yourself to another world to experience something fantastic. I think it is totally acceptable to have elements of the game to have an incredulity or to focus on how cool something looks as opposed to how believable it is in real life. However, I think having an option of where to put the weapon as an extra layer of customization would be acceptable, and I would also encourage it. DnD is afterall all about personal choice. I just would rather not see historical accuracy enforced on anything and that goes for armors and shields too.
That's well and good, but in some cases looks utterly ridiculous and makes no sense... like rapiers or hand crossbows worn on the back. I can certainly see longswords, greatswords, -axes, -clubs, polearmss, bows and crossbows as being worn there, but small or lighter weapons like a rapier, scimitar, hand axe or hand crossbow should definitely be worn on the hip.