Uncle Joe just made a remark that gets your riled, and though you are naturally animated when speaking, it's probably not the best idea to wave your cutlery in his direction. Worse case scenario - you stab your uncle. Best case scenario - you look like a fool. Just avoid waving it in the air while making a point. If you must, put down the fork and knife and use your hands. At least then the guest sitting next to you doesn't have to worry about getting an eye poked out, or sauce on their clothes. And you'll be saved the embarrassment.
We'll give you a Two-fer of advice here. If you would like to have something at another spot on the table, it is impolite to reach across another person's place to get it. Ask the person (by name) closest to the item if they'd pass it to you, "Sally, would you please pass me the salt". (please is always good) Generally if there is a lot of noise, or deep conversations happening around you, by addressing a specific person, you're more likely to get the object you desire without shouting over everyone. In these scenarios, if the person is all the way at the other end of the table, she will pass it to the next person until it gets to you.