Besides carrying the standard, would a standard bearer typically have any other duties?

The standard bearer’s primary role is to motivate and help direct the troops by showing them which direction they were to go and where they should rally to in the confusion of battle – thus why standard-bearers were chosen from among the strongest and bravest, to make sure that they would be right at the front of every charge and would never abandon their position even in the most dire situation, which in turn would ensure that the soldiers looking to them for guidance would not go astray. 

In the Middle Ages, it was also common for standard-bearers to act as bodyguards for the lords and kings whose banners they held. For example, at the Battle of Bosworth Field, when Richard III made his suicidal cavalry charge intending to kill Henry Tudor, Sir William Brandon (Henry’s standard-bearer) placed himself in between Richard and his prey and was slain by the king, saving Henry’s life. Equally impressively, Richard III’s standard-bearer, Sir Percival Thirlwall, kept the Yorkist banner flying even after losing both of his legs.