Escrima Sticks

The Escrima Sticks are a pair of specialized batons wired with tasers, and are an indispensable item in Nightwing's combat style.

Arkham City Incident
Nightwing used his Escrima Sticks to protect Wayne Manor when Batman was in Arkham City. He used those against Hugo Strange's TYGER Guards.

Before Arkham Knight Incident
During the assault orchestrated by Harley Quinn at the Blüdhaven Police Department, Nightwing attempted to stop her, but to no avail. He focused only on the taser stun technique, thus Harley was able to exploited the weakness and struck him down.

Arkham Knight Incident
Nightwing once again employed his trusty Escrima Sticks against wrongdoers, and this time it came with advanced utilities, such as being able to be thrown, forgone from using his Wing-Ding completely, and the ability to generate electric shockwave upon ground impact. Nightwing fought off Penguin and his arms trafficking contraband in Gotham City alongside with Batman. Sometimes later, he joined Batman on the Iron Heights Penitentiary in an attempt to apprehend Killer Croc.

GCPD Lockdown Incident
Nightwing retained the weapon as part of his new arsenal in this incident. He used them with grace while defeating The Penguin's Henchmen trying to jailbreak Penguin in GCPD.

Gameplay
The Escrima Sticks are used for the most of Nightwing's combat. They also could be used for most Takedowns and Special Combat moves.

Nightwing could throw them into enemies, which left them stunned, opening up for further Beat Down. The sticks are retractable and ricochet off of surfaces.

In the Harley Quinn Story Pack DLC boss battle, Nightwing's only attack with the Escrima Sticks was a simple lunge and swipe, which was similar to a regular stun baton attack.

Trivia

 * Like Robin's Shurikens, Nightwing's escrima sticks are real life weapons being dual short staffs used in the Philippines. But, as aforementioned, Nightwing's billy clubs were wired with tasers.
 * According to Nightwing in GCPD Lockdown, the tasers can generate up to 50,000 volts.
 * Barbara Gordon kept a pair of Escrima Sticks in her backpack for self defense, according to one of the Arkham Knight's soldiers. Humorously, they refer to her weapons as "a couple of ninja sticks," despite having previous experience in warfare.