Ghosts, Wraiths, Specters, etc and Physical Objects

Hello, I have been searching for some kind of definitive take on this, but I'm not finding clarity in discussion. Can "spectral" or "incorporeal" creatures pick up/manipulate objects or use physical weapons? For example, could a group of specters haunting an old fort still equipped with siege weapons use them to attack approaching creatures? Without any explicit statements in the rules texts, I'm guessing it's the DM's call ... "Incorporeal" is only used to describe that movement trait rather than dictate anything else about how the creature operates. Thanks! T

They absolutely can. The trait says that they "can move through other creatures and objects". It's is their choice to move through things.

As an example of this exact thing, the Poltergeist has an attack right in their stat block called "Object Slam" that deals bludgeoning damage.