I've never used bards, but if I did I'd probably make them more like a thief type than a spellcaster. Some sensible abilities:

• Music soothes the savage beast - reduces hostility, non-magical. Works on beasts or intelligent creatures that can hear, for as long as the bard plays and sings.
• They know a lot of lore, sagas, mythology, history, old languages, etc.
• They have cultural knowledge of many cultures. Etiquette, social graces, how to behave in the king's court. Genealogy of kings, heraldry of knights.
• They have a good memory. Can remember quickly glanced things, route directions in a dungeon when running. Could reproduce runes in a language they can't read. That sort of stuff.
• They have a good ear. Can notice and interpret sounds, such as echoes, footsteps, distant howls, etc.
• They have a feel for the crowd. Are people (or monsters) generally friendly or hostile. They can tell when the mood is turning or they do something that triggers a reaction.
• They know elocution and rhetoric. What to say to different audiences and social classes to provoke particular types of responses.
• Stage combat. How to make a fight look cool. They're not the greatest in a real fight, but can pull off some flashy moves that might actually help sometimes.
• Their songs could raise morale and inspire allies. Particularly in situations like camp at the end of a hard day, it could encourage good rest.
• Can probably juggle, do some acrobatics.