Most games have characters with pretty straight-forward abilities; shoot dudes, beat up dudes, whatever. Some games that give you some supernatural ability, or at least non-standard (I can't say unique, because many of them appear in multiple games) game mechanic. Many game have a small portion at the mid-way point, or near the end with something like this, but other games go so far as to base the bulk of the game around one of these mechanics. For lack of a better term, I usually call these "Shooters-with-a-Gimmick", though I don't mean "gimmick" pejoratively,and they aren't always shooters.
For whatever reason, some of those games, decide part way through that you aren't allowed to use your interesting abilities anymore, and fall back on more traditional gameplay: they Nerf your powers. I don't understand why they do this. (Well... I can guess: time constraints; lack of creativity). After all, why bother giving the player a neat toy, which supposedly forms the core of the experience, only to render it useless later on? The player is presumably playing the game in the first place for the "gimmick", and you are forcing them to fall back on more common game mechanics, which probably aren't very well implemented anyway.