Fine-Tuning the Bard

In Dungeons and Dragons, players choose from a number of classes drawn from high fantasy tropes: fighter, thief, paladin, sorcerer, ranger, and so on. Each class has its own mechanics and flavour, with some focusing on hand-to-hand combat, others on spellcasting, still others on adventuring utilities such as tracking or finding and disarming traps, and so on. 

The bard has been called D&D's "jack of all trades" class because as a bard, you have access to decent spellcasting and martial abilities. But here's the problem: bard magic comes in the form of performance. During battle, the bard accesses their magic by singing, playing a musical instrument, or some combination of same. Yet, at the same time, bards can also enter combat with weapons such as sword, clubs, crossbows, and so on. While this is plausible in some combinations--for example, singing while using a sword--in most situations I have a hard time imagining what's happening the world if the game while the bard player is banging bongos while somehow at the same time wielding a bow and arrow. 

It seems to me that bards would be much more interesting if their magic worked only while they were actively playing an instrument or singing; the moment they stop (or are stopped by enemy action), the spell effect ends. 

This would require trust and teamwork among players. For example, let's say that Bardolemew Muse is a level one bard. Bardolemew has two spells: Beast Soother and Strumming Shield. The first spell puts dangerous wild animals into a sleepy, contented state while the second creates a bubble of shield energy around anyone within five feet of the bard. Both spells are activated and maintained by the bard strumming their lute/guitar/banjo/etc. 

Here's how a battle might look: Bardolemew and his companions Bash, Tumbler, and Milqueboast are set upon by a group of bandits. All players and the DM roll initiative as normal, and when Bardolemew's turn arrives, he begins playing "The Ballad of Raven Nevermore," activating the Strumming Shield. The glistening, sparkling shield bubble pops into existence around Bardolemew and his friends, raising everyone's armor class to 20, assuming they stay within the bubble. Bardolemew must keep playing to maintain the shield, and his companions must stay close to Bardolemew to enjoy its defensive effects. However, they can happily engage anyone just outside the field with melee weapons, or use spells or ranged weapons on anyone further than 5 feet away. As the battle evolves, Bardolemew may choose to end the song and drop the shield should the situation warrant it; perhaps most of the bandits have been killed and Bardolemew wants to switch to using a sword to slay the last bandit, given minimal risk to the rest of their team. 

Of course, for this game mechanic to work properly, you'd have to boost the power and usefulness of bard spells to overcome the handicap of needing to remain focused on playing their instrument. On the other hand, I think the mechanic could also be more inclusive of different types of performers: for example, dancers and actors might maintain their spell effects through their particular talents. 

What about singers, though, and other musical talents that leave one or both hands free? I think in this case I'd probably break them out into a separate class, giving them spells less powerful than my proposed new bard class, but more powerful than the existing 5e bards. They'd still need to sing or play their one-handed instrument (harmonica, maybe?), but their hands would be free to use melee or ranged weapons at the same time. 

I'm not a game designer, so of course I don't know if my bardic notions are feasible. But I think, if the mechanics could be worked out, it might make the bard class, and Dungeons and Dragons itself, a little more flavourful.