I know at least one witch who puts a powerful hex on her bottles as an attack against anyone who threatens magic against her.
I use mine for a slightly different purpose. As the bottle represents me, I use it a bit like a poppet. So if I am tired and have to go to work, I place my bottle in comfy blankets to make me feel rested. Or if I am hot I will dunk it in a bowl of cold water to cool down. Its an unconventional use but a very useful one.
Picture is of my own current witch bottle. I will be doing a blog on my serenity bottle shortly.