House Rules on Proficiencies

I realized last Wednesday that I don't have a good grasp on what different proficiencies do, particularly those not likely to be taken by wizards. So I'm looking through the relevant chapter to see if I can't get some idea on how they work. As I was doing so, I came across the bribery proficiency, and decided to change it a little.

Bribery: As written, this proficiency allows the PC to offer bribes, with bonuses based on the size of the bribe. Since I want any PC to be able to offer a bribe, I need to amend this a little. Now, when offering a bribe, any character can gain a +1, +2, or +3 to the reaction roll for bribes equal to a day's wages, a week's wages, and a month's wages, respectively. But if you take the proficiency, you get double the bonus.