Hey everybody, thanks for the answer once again 
I’m ashamed of myself, the thing I was looking for was UV Mapping. I didn’t even know what that meant until I looked it up lol. But now (as per the usual) I have more problems.
I’ve watched several Tutorials (Both are for Cinema 4D, but I’ll show the links to them further down here anyways) and followed them Step by Step. I really liked the result of the layout this time, so I thought (by the looks of it) this time it might work. But it didn’t. Again. Quixel just can’t get it right, and now it messes up more than before. I’ve exported a more detailed version of the sword (this one now has a tip – Whoo-hoo ) and exported JUST ONE object. There was nothing else there. Absolutely nothing. Not in the Camera View, and not in the Browser. But now when I import that *.obj file into Quixel, it now shows both of my Swords. My old and my new one. It layers them on top of another and has just pasted the texture on the top/older one (It didn’t even get that right…).
So I really think Quixel is messing up for me, i.e. it is totally useless for me now (good think I stuck with the demo and didn’t instantly buy it).
Can you guys recommend anything else? Anything that works without Photoshop please. I was pretty “mad” (madness lol) that they didn’t tell me foop about me needing Photoshop for their Product. I think I’ll go for the Substance demo next.
Tutorial Links:
TUTORIAL Cinema 4D & BodyPaint - Texture & UV Mapping - YouTube (<— This one is italian. But you don’t need to understand what he says, just watch out for what he does, it helped me a lot)