Slow enemy projectiles in mid-air with the TimeSaber. Remember, the "time field" extends from the blade-edge of the TimeSaber, so you must weild it properly to slow the projectiles down.
Mission 4 is the only Mission in the game with the TimeSaber, but there are some other weapons for you to experience in the full game.
I haven't decided for sure, but the demo may only be downloadable for a limited time.