How to care for leather equipment when it has been very damaged by rain?

It is really important to immediately oil it!
Depending on the type of leather (open grain, full calf, leather with a protective sheen) I wouldn't oil and then condition lightly. Let it dry before doing anything else
I like to use tack waterproofing products (there's hundreds). Right after something gets rained on or too wet. Once it's dry oiling it is what I find best
There are a water-resistant leather conditioners out there. I believe Leather New is one of them, I use it and I'm really satisfied with it :)
There is also tack cleaner that makes your tack water resistant. I have used it. It's like a leather conditioner that helps when it gets wet. I don't really know how well it works, I just used it once because I ran out of other tack cleaner.
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