go through your vault, fill up your inventory with weapons you thought might be good when you stashed them, then run around in some low-end content (not so low that everything is OHK), and see if you actually like how the gear performs and if you would want to use It in the future. If you're holding on to some event weapon with a unique roll, but you test it out and it doesn't really work that well, it's better to just scrap it. Souvenirs are another thing, and I have plenty of them, but most of my vault is junk I haven't got around to testing, or I'm only keeping one copy of a weapon because there aren't exactly any replacements for it.