I have an iPhone 5S and an Apple Watch both on iOS 9 and WatchOS 2 respectively. I've been trying for the last day to add my Discover Card to no avail. From what I was reading Discover card was telling customers they NEED an iPhone 6 to do this. This is incorrect!
You can have a 5S and an Apple Watch with your Discover card. A user on Macrumors was able to provide insight. Unpair your watch from your phone. Then repair the watch back to your phone, you can restore from backup when you repair so none of your settings/apps have to be re-setup. Once that is complete, shouldn't take more than 20 mins, go ahead and try to add your Discover card to your wallet. Should work just fine. I was able to add my card after this. Good luck!
