The Japanese army did not arm its soldiers with katanas, and before the Meiji Restoration there was a sword ban on people outside the samurai class. The swords used by the Japanese Army were called Guntō and until the 1930s, a European style sabre was carried as a symbol of rank by officers. In the 1930s, the style of the Guntō was changed to a more 'traditional' style, and varied wildly in quality. It shouldn't be considered archaic to utilize swords as marks of rank by officers, as there is great precedent for this in European armies. By the end of WW2, the practice had died out, and thus there was no reason to issue swords. Could someone who knows more than me please expand on this?

In 1876, the Japanese Government issued an edict called the "Haitōrei", otherwise known in English as the "Sword Abolishment Act." The act was one in a series of reforms designed to disembowel the entrenched samurai class and came shortly after the government approved a Western style of sword in 1875 for use in the armed forces. Notably, the act did not prevent males of the former daimyo class from carrying swords as this had been previously agreed upon as a right of the peerage when the daimyo and kuge class were merged to form the kazoku in an effort to mirror the British aristocracy. While the use and wear of swords abruptly disappeared from everyday Japanese life, many former samurai and kazoku families continued to keep their swords in storage or, possibly, on display in their home.

The new sword authorized for the Japanese armed forces was called a guntō in order to mentally separate the object from its former purpose. There were several versions authorized that depended on the owner's rank (officer or non-commissioned officer) and service (army, navy and police).

In 1934, the Japanese Government announced a new series of regulations that eliminated the previous style of guntō in favor of a nationalist style of sword based on the old daitō of the pre-Meiji era. While the police continued to carry the "kyū guntō" or old style of sword (Pic), the armed forces began to carry the "shin guntō" or new style of sword (Pic). Like the kyū guntō, the shin guntō had variations based on one's service although the largest distinction was between officers and non-commissioned officers (Enlisted men had no swords.). All non-commissioned officers were issued with a mass produced sword made of rolling stock in a factory. They were utterly identical except for variations in production methods, but non-commissioned officers had no option to personalize or otherwise make minor adjustments to their swords. Officers, however, were issued with handmade blades when available. More frequently, they remounted ancestral blades into shin guntō mounts as a large number of officers hailed from the former samurai class or the kazoku.

The Japanese Defense Force continues to authorize their officers to wear swords, although they are similar in nature to the kyū guntō and rarely seen except on the most formal of occasions.