I think it sounds cool in practice but considering Thedas, for the most part, is based off of medieval warfare, it would be difficult to implement lore wise. Most people fight with pikes, swords, maces, bows and magic and probably wouldn't consider unarmed brawling in the first place (even Origins/DA2's tavern brawl was settled with martial weapons). Also, the Silent Sisters seem like a very isolated, very specific group that even most dwarven groups wouldn't consider fighting unarmed.
However, a Silent Sister companion with a unique skill tree spec wouldn't be such a bad idea. Like Varric, she has one 'default' style (unarmed, she can't equip weapons) but she can be specced as an archer as well. Of course, given she's silent, it'd be better to reserve her as a DLC companion. (Would love and hate to see Vivienne/Dorian's remarks, probably not the nicest, while she'd probably earn Iron Bull and Cass' respect given her toughness and dedication).