A Samurai must never appear unarmed even in peace-time. Katana and wakizashi are parts of daily dress for going out.
Wakizashi is worn at home as well (optional), but katana is not to be worn at home except in times of war. You must store the swords (katana, wakizashi, tanto) at the best place in the house. This in Japan means the best room for receiving guests, named
tokonoma. At the place is also kept yoroi (armor). All of them must be cleaned and kept from dust everyday. You must clean the blades yourself to keep away rust. This is not a job for servants. The idea is to keep the close relation between you and the weapons, which are a reminder of your duties and obligations.
Wakizashi is a Samurai 'name card.' It should be left on the body of the man you kill in a vendetta/vengeance, as your responsibility of the death as well as the reason why.
You must never let anyone else touch your swords at any time, except for servants who handle storage of swords of guests (katana only) when you visit another Samurai's house. Upon a visit, you must leave your long sword/katana with the servant of your host, unless your intention is unfriendly. If you sit alone in someone else's house, you may put your sword next to you in any fashion on the floor.
When you sit with a host or a guest, you must put your sword at your right side. This indicates friendly intention. If you are invited to a suspicious neighborhood or environment, or you are not in good relation with the host, you must put your sword at your left side, and get ready to draw it if necessary. In short or hurried visits, you may keep wakizashi on your girdle. In parties, you must leave wakizashi with the servants, and keep only tanto.
Clashing a sheath of one's sword against another's is a breach of conduct. You may demand a duel on such occasion, and the other Samurai may do the same. To turn a sheath in your belt under someone else's eyes means a tantamount challenge to fight. Hence do not even touch your sword that you are wearing, when you don't mean to have a duel. No weapon at all, including tanto, is to be displayed drawn out of the scabbard, for any reason.
Do not request to see a sword of another Samurai, unless you have a very good reason to do so (to examine a very famous sword, you are an antique collector, etc.).
Upon going out, Samurai ladies may wear wakizashi (optional), and tanto (must-have). The etiquette is the same as the above.