The word "gage" is a noun that typically means a form of security or a pledge, such as collateral that is given to ensure that a debt or obligation will be fulfilled. It can also refer to a challenge or a test of skill.
In closing arguments in Manhattan Federal Court, former Senate Majority Leader Dean Skelos» lawyer Robert Gage said his client's three week long criminal trial showed no criminality — just a father trying to help his son. (nystateofpolitics.com)