Why military weddings have the arch of swords ceremony

But why is the arch sabres (which is omitted if the bride is a fellow officer) observed?

When a soldier weds, mostly in crisp military uniform, the bride and groom step out of the church and march under outstretched swords forming what is called the arch of sabrEs. Indeed, military nuptials in church or military chapels are like other civilian weddings, just that they’re differentiated by among others; the absence of suits (although some sport them) and the couple marching under the honorary arch of swords. Even when it rains, the arch sabres ceremony comprising six or eight officers is performed inside the church or chapel!

With permission from the presiding clergy, an officer can have two arch sabre ceremonies inside and outside the church. The sabre bearers are normally officers of similar rank who take positions up with their sabres touching the tip of the sword. They stand such that there is enough walkway for their recessional as they pass through without squeezing each other out of line.