Some miscellaneous rules ideas.
Add IQ/3 (round down) to your base Bard Skill, and +1 for every level of Charisma (if any). Use the new rating for your effective Bard skill for one roll only. This extra effort costs a point of fatigue to represet the wild gesticulations and brow-furrowings you need to do. On a critical success, your audance will take up arms and offer to give up their lives fighting for you. On a critical failure, they think you're a huckster and want to hang you from the nearest tree.
One shortcoming of this is that the scale isn't quite right, i.e. +4 can make a big difference in real life, but doesn't make *quite* as big a deal using the "no roll" approach I've described. I might draft up some new numbers for the reaction table that would scale better.