My habit seems to self control. I buy as much as I can, then have to sell it to buy something even more expensive.
Other than that I try to pick narrow areas of focus and make the weapon buying more like a personal research project as I learn about a period of history. I tend to like to immerse myself in a specific sub topic so I narrow the collection to fit that. Then latch onto another topic and continue the process.
I agree with fearn about the care taking aspect in all this. I see no point in hiding pieces away and if I haven't looked something over in a while I'm ready to let it go. I also find that certain pieces I develop a personal connection with and others I don't. Not sure why, just how it goes.