In the current world we use playing an instrument to resolve some major quests, faction tasks, small buffs, and charm animals.
The situation right now is that a person has to select their instrument, stop moving completely and then focus on the Guitar-Hero style mini game to play a small section of tune.
What I am picturing is that our character knows the instrument already since they have had it since childhood and that they use it all the time.
A new goal would be to collect entire songs and play them from memory while on the move (like choosing a song from the soundtrack), letting players set their own pace. Now that they can just play on the run, the choice of song provides passive benefits to the player and their friends, or negatively impacts enemies - but since every player knows how to play their instrument, they all have 'Bard' potential and could learn more in the future.
Are you charging into a fight head on, giving and receiving large amounts of direct damage with melee weapons? Play a battle fanfare which boosts physical traits. This would be fantastic to do while mounted.
Do you want to reduce the defenses of enemies, make them confused and uncertain, or increase the amount of time it takes to do things like trigger an alert or cast a powerful spell? Play a haunting dirge as you sneak around - your connection to the spirits makes the atmosphere feel heavier. They believe they are surrounded, and their odds of winning are hopeless. Maybe some of them will just throw their weapons on the ground and retreat?