What are the global restrictions of making an unarmed strike? As it is considered a weapon, I suppose one must have a "hand free" to "punch". However, there are some gray areas I can't find any answers to.
For example, the Monk class allows a player to add an additional unarmed strike to his Attack action, as a bonus action. If one is using a Versatile weapon, can he attack using both hands, making the damage 1d8 and still make use of his additional unarmed strike(s)?
Additional remark: The extra unarmed strike granted by Flurry of Blows has no restrictions regarding the weapon(s) held. Am I missing any implied restrictions here? Or is a Monk somehow able to hold a two-handed weapon and still make use of Flurry of Blows ? If that is the case, I am to believe the unarmed strike from FoB would not be considered as weapons. Would that also mean that if a monk is wielding a quarterstaff with two hands, he could open with an attack of [1d8 + Dex] damage, followed by an unarmed strike of [1d6 + Dex] damage with a bonus action (using Martials Arts) ?