The meanings of fake and faked are slightly different. Something is "faked" if it is trying to come off as something else. A knockoff Gucci watch is "faked" because it's not really made by Gucci. A "fake" watch means that it is not really a watch. Hope this makes sense! Let me know if you need more explanation.

1. This is a fake watch. ("This is a faked watch" does not make sense, because it is hard to conceive what it means for a watch to be "faked." On the other hand, you can say a "faked death" when someone somehow caused others to believe he is dead, perhaps to escape the law or other types of punishment). 2. I bought a watch, but soon realized that it is fake. (Same reasoning as above). Basically, fake = 假的，faked = 假裝的。 說「這手錶是假的」很有邏輯，但「這手錶是假裝的」不通吧? 但為了逃澼法網，有些人會不惜「假裝死亡」所以說 "faked death"是沒有錯的。