Bard's Ax

Any musical instrument, tenderly crafted by a masterful artisan, may be considered as a Bard's Ax. Pieces of magic are attracted to such an item, and gifted musicians feel empowered while playing them.

A Bard wielding their Ax is better able to concentrate on their art, turning a single Bardic Inspiration into a grand performance. As a bonus action they can start or maintain this performance with a successful skill check against a DC equal to 10 + the number of rounds being played. (11 for the first round) As an action they can re-roll against the current check.

Some other rare builds exist, allowing for greater displays. Some instruments amplify spell casting during the performance, while others grant amazing effects the longer the song plays. 

Notes: proficiency with performance