Death means death. Dropping to zero hp and failing 3 death saves, massive damage, being disintegrated, being turned into green slime etc.
What is open is whose death, yours or the fighters.
If you are dead and the fighter is still alive, do they continue to serve you? That is will they attempt to rescue your body and seek out some means of returning you to life or is the bond broken?
Similarly, if the fighter is dead; while they obviously can't serve you in that condition, if you were to have them raised would the continue to serve you as part of the magic or would the bond be broken? If the bond is broken, would they serve you because you are a really good bloke and had them raised from the dead; that is, would they be loyal but for prosaic rather than magical reasons?
Given that death is not necessarily permanent in D&D these are things that are worth thinking about. There are no right answers and however you choose to interpret this is fine but it is better to think about it before it becomes an issue.
Incidentally, as a long term D&D group our practiced response to finding a Deck of Many Things is to put our hands in our pockets and walk briskly away. We invest too much in our characters to chance everything on the flip of a card.