During the duel against Bahadur, Daryun chose the sword instead of his preferred weapon, the spear. However, a sword would be more useful and convenient in a close combat fight, even when broken, as seen when Daryun used the broken sword to stab Bahadur.
If Silvermask hadn't revealed himself to Bahman or been hasty in killing the guard, he could have easily cornered Arslan and killed him without anyone being the wiser how he got into Peshawar.
