Lights for a wedding

I have a lighting quandary. I primarily shoot weddings, and am often in dimly lit locations, and bring colors back up in post. Obviously having some sort or light would help to get better color and remove some of the grain I am getting in my shots, but I am always concerned about showing up with too powerful a light and disrupting mood that is being set.

I use Canon HV20s, can anyone confirm that getting by without a light is okay, or if someone has experience and knows of a light that will give me a better shot without it seeming as if I am casting a flood light onto what I am shooting?