Actually using a light under water is something else than incidentally allowing it to get wet in rain.
I would feel quite confortable walking around in the rain with an IP-8 certified light.
And even that I would not do without first checking if all seals were in the right place.
Swimming around with a light causes pressure peaks that are higher than gently submerging it.
Turning on a high powered light in cold water just adds extra pressure.
Look at a typical dive light and you know they are are not built from the same perspective.
A Convoy S2+ is absolutely not fit for wet weather, but I do love my S2.
That little light tries to keep the water out with 3 (single) O-rings and a rubber tailcap.
I would open it every time I use it when it rains. Clean it and let it dry.
My Ledlenser D14 consist of only two parts, the head and the body-tail, and has double O-rings.
The switch operates with a magnet. Magnet on the outside, switch on the inside. No chance of immersing.
And yet it is only rated at 40 meters.
NB there is a big gap between any item that is called waterproof and a real dive-item.
Experts say it is safe to take your 100m waterproof watch into a swimming pool, if you don’t play rough.
If you would like to snorkel in shallow water, use a 200m waterproof watch.