There is no classes who is tertiary or even secondary at combat in DnD. Bard are 100% useful in combat.I can understand that. Maybe I am not explaining things properly.
If anyone has played any of the White Wolf games, you chose primary, secondary, and tertiary attributes. Tertiary would be like a 10 to 12 stat (say strength), the secondary would be like a 14 -16 and the primary would be like an 18-20. So a front-line character like a fighter would be combat primary, chooses exploration secondary and social tertiary. A Bard might be Social primary, combat secondary and exploration tertiary. Does this make sense? Everyone can do everything but some are better at certain things while others are better at different things.