You can neither jailbreak nor downgrade iOS 6.1.3 on the 4S with or without blobs.
As far as I know, there is no WiFi bug of 4s phones with iOS 6.1.3. What is the problem that you are seeing?
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Perform another DFU restore using iTunes. That solves the problem in all cases I've seen.
If you're still under warranty, bring it up with apple and potentially get a new one. Otherwise, I guess you might have to try the blow dryer / freezer method
There won't be a jailbreak for A5+ devices on iOS 6.1.3.
It's not whether Apple allows it, it's whether there is a jailbreak available. Jailbreaks rely on exploits and vulnerabilities on the iOS or on the device itself or both. They don't spontaneously come together. Jailbreaks have to be made and coded