"Combat" in the astral has been such a non-issue across my experiences that it's honestly something I wouldn't even advise people to bother preparing for. I'm sure it's out there if you go looking for trouble, but fights generally aren't going to come to you unless you're seeking them out. Anyone expecting an astral battle where they're fighting off armies of demons with a sword is in for a lot of disappointment, since the most effective weapon there is just calmly pushing a spirit away.
I did used to have an unfriendly entity hanging around my house, most likely a thoughtform courtesy of an old church group I was part of that convinced themselves I was being haunted by a demon. It attacked me in the sense of conventional physical violence only once, across more OBEs than I can count. I got my ass kicked, because I was just passively letting it happen and felt no concern or drive to fight back. It didn't hurt or leave me injured, and from what I can tell the whole thing was a failed scare tactic rather than anything that could have actually hurt me.
Interactions that were unpleasant but not violent have gone the same way; I stayed unbothered about whatever was happening, and only even felt the need to leave if I decided there was something else I wanted to do. If the spirit was being especially annoying or persistent, pushing it out of the room became easy enough with minimal practice.
I don't tend to be a huge social butterfly trying to seek out people to talk to when I'm out of body, but the majority of spirits I've met were very benign and mostly just concerned with their own affairs. The typical pattern during interactions is that they'd be a little confused when I approached them, but not interested enough to question anything or try to stick around and make friends.
