Boomerangs his lightsaber throw, striking two people with it

Understanding as much, the Emperor's executioner was moving faster now. A jump carried him to the rampart, just short of the lowering shield, where he did something so unexpected that it took Shryne a moment to make sense of what was happening.

Vader hurled his ignited lightsaber through the air.

For a split second Shryne thought that he had done so in anger. Then, in awe, he grasped that Vader had aimed.

Spinning out from under the lowering security grate, the crimson blade sailed high over the crowd, following a trajectory that took it north of the landing platform; then, on reaching the distal end of its arc, it began to boomerang back.

Shryne flew for the top of the stairway, his gaze frilly engaged on the twirling blade, his heart hammering in his chest. Calling on the Force, he tried to influence the course of the lightsaber, but either the Force wasn't with him or Vader's Force abilities were overpowering his. The blade was whipping toward the landing platform now, close enough for Shryne to hear it whine through the air, and spinning so swiftly it might have been a blood-red disk. Passing within a meter of Shryne's outstretched hands, the lightsaber struck Fang Zar first, ripping a deep gouge across his upper chest and nearly decapitating him; then, continuing on, it struck an unsuspecting Jula across the back before completing its swift and lethal circle and slamming into the upper reaches of the fully lowered rampart gate, where it switched off and plummeted to the paving stones with a metallic clangor.

Dark Lord: The Rise of Darth Vader, Part III, Page 253