Do martial arts double knives have to be put in sheaths?

This knife must be wrapped in a sheath.

A major feature of traditional double knives in China is that a pair of double knives are inserted in a sheath. This method of carrying two knives in one sheath is relatively more portable. If you hang a knife on each side of your waist and walk in the way, the sheath will kick your leg.

The disadvantage is that the scabbard is a little slow, and there is an extra action of dividing the knife with both hands after the knife, but as long as it is not a close-range sneak attack, it is not necessary to scabbard quickly.