Ah, the Bard. Commonly regarded as the worst class ever. I like the Bard however, and I think there is a place for them in my B/X inspired adaptation (need a good, short catchy name). In my B/X thing I want there to be a class which pairs directly with each ability score. For Charisma the class will be the lowly Bard.
I don't want my Bard having any real arcane spell ability, instead they gotta use their pure Charisma and musical talents to bring them victory. To this end, the Bard will be fairly combat capable but also needs more abilities to balance not having spells. I'm thinking they can try to charm and distract opponents with their music, inspire their friends and confuse their enemies. The Bard can also use their music to cancel certain charm and magical type effects which could harm the party. A bards music can cause some spells to fail. Additionally the bard will be very likeable because of their hopefully high Charisma, able to open doors for the party in town that would normally need to be kicked in by the fighter.
I know what I'm describing sounds alot like the 3.5 bard sans spells but I think in an Oldschool game those powers jump up a bit in terms of utility. Individually each little power I describe may be fairly insignificant, but when put all together it should create a class that is almost always useful to have around.