A fair amount of times I encountered beings that carry or use guns and I got very afraid everytime, because I have no idea how to protect myself from it. It's such a pathetic idea of a weapon I get angry even thinking about it. Swords are much fairer, they are like an extension of your willpower and fighting is more like a dance, but guns? you just pull the trigger and in an instant you hit the target.. it's just cowardly. Maybe It's not as bad as I think and they work differently in the atral realm. How much damage do they do? It has to relate with the shooters willpower does it? Any tips?

I don't think it's cowardly. Each to their own, and while it seems simple and devastating, (and depending on whom is on the receiving end, it is) there's lots of ways to counter it.

For myself, it's the same as countering any projectile (which there are plenty of. I would be more worried of magick-blasts than someone firing a small metal piece at me at high speed astrally) with a force-field shield.

I don't know what you mean by damage, as it depends on what you're wearing, how you regenerate energy, and so forth. They are guns, you can correlate a typical one to how they would work here, on the earthen plane, in normal circumstances.
If the bullet is enhanced, or the person shot is, etc etc, lots of variables, then there will be different outcomes. If you mean astral injury, it can mess with your energy like any damage does, and varies depends on how severe it is.

I don't believe it's correlated to the shooter's willpower though.

How I defend myself against projectiles is either by avoiding them, if they are slow enough, and if not, I use barriers and energy-shields. If you ever seen Norigami, the borderlines in there is a good example. Except smaller.

Hope this small piece of advice helps.

Energy projectiles aimed in your direction can be converted into something harmless. One can will them to transform into some other form of energy that won't cause any injury. Picture a drop of water or a handful of cornstarch. Or if you want to get on the assailant's nerves, picture something festive like rainbow glitter. 2yn You get the idea.

A gun isn't more cowardly then any other weapon, like Vey said, it's a choice. If you want it, you could say: a astral gun is a device, which uses magic, because most of them shoot energy/elemental projectiles~ It's like saying magick is for cowards (which actually sounds like something I would say, muhahahaha)
Blocking a projectile is easy. You just need to visualize a wall infront of you, which let's the projectiles go "poof". If the one, who shoots the projectiles, has lesser willpower than you, it will go "poof".

My hate towards guns was adressed mainly on their use here on earth, I'm yet to be hit by one astrally.
Now that I'm more educated on the means to deal with them I'm convinced that they're not even half as bad. Those are really good recommendations, thank you all. Oh, and yes I have seen Noragami actually. I will definitely try the borderwall and maybe the projectiles becoming marshmallows .
More thoughts and suggestions are still appreciated

Bulletproof vest

Not like you're going to die in the astral. These kinds of duals test your own will power and courage. You can easily use some super astral energy and block that bullet matrix style. It's all about controlling your visions.

Would a courtwind angel not be able to just guide you out/away from such situations?

A forcefield, definitely! Or if you have any protective being under your keep you may ask them to accompany you in your astral travel And lol u watched Noragami damn it's an awesome anime hehe pretty good inspiration for spiritual stuffs too!

Maybe you could make it so you somehow sabotage the guns the second they are aimed at you or someone you care for