You have contracted a transdimensional bacterium called malaise, which causes a condition that has been colloquially dubbed as 'Lazarus Syndrome'. This bacterium completely rewrites their host's personal dimensional structure, rendering them completely immune to any forms of premature ceasing as to preserve the host and in turn themselves. This typically manifests as the ability to come back from the dead.
But this isn't the end of your new abilities, however. The second most prominent effect Lazarus Syndrome causes is to occasionally generate powers in relation of how you died. Death by sword? Maybe you can disconnect your body parts, or perhaps become very good a swordplay. Death by crushing? Perhaps your body will become super-dense or allow you to become intangible. You never really get to choose, but it'll always be related to how you die. The more you know how you died, or will die, the more you can narrow down what power will manifest.