A wading staff is a very important part of a fly anglers equipment. Safety is of course very important! But when you are in fast moving water, as well as safety, a wading staff gives you an extra piece of confidence and reassurance. Just pass the loop over your wrist so that if you need to use that hand in a hurry you are not going to lose your staff!
Importantly however is to remember never to lift your wading staff up until you have both feet firmly planted. A wading staff gives you a third leg and you should always be sure that 2 of those 3 legs are solidly planted at all times. If you can, use a wading staff in the upstream hand to give you maximum benefit and support!