Why did the lady at the armory shop say that Lieutenant Henry didn't need a sword if he was going to fight at the front?

The lady in the shop says this because a sword wouldn't be of any use, only guns.

“Have you any need for a sword?” she asked. “I have some used swords very cheap.”

“I’m going to the front,” I said.

“Oh yes, then you won’t need a sword,” she said.