
As Luke, and then the Rebellion as a whole, learns, the second Death Star is fully armed and operational.
Obfuscating Disability: It's designed to look not-quite finished, with massive gaps in the superstructure (and technically speaking, it isn't actually finished by the opening of Return of the Jedi). Deflector Shields: The new Death Star is protected by one, generated by a station on Endor.
In canon, IG-88B made a similar attempt, but was thwarted by an astromech droid aboard the station.
Adaptational Nonsapience: In Legends, IG-88A secretly uploaded his consciousness into the Death Star's central computer, becoming the weapon in the process, and intended to use it to instigate a droid rebellion, only to fail before he could start when the Death Star was destroyed. However, it also served another purpose which involved luring the Rebel Alliance into a battle which would annihilate them once and for all. Similar to the first Death Star, this station was designed to terrorize planets and star systems.
A partially complete space station that served as the successor to the original Death Star.