Semaphore has been on a roll lately, as shown by the release of yet another TinyUmbrella beta build, and this version contains a significant new feature. You now have the ability to save SHSH blobs directly from a local device. This means that if you're on a jailbreakable firmware like iOS 8.1.2, you can save the 8.1.2 blobs even though Apple is no longer signing that firmware version.
TinyUmbrella can now save local SHSH blobs from device, and that includes iOS 8.1.2