What should I do with my gear? Should I save stuff that has effects I want? Don't know what mechanics there are to unlock later, so I've been kinda hoarding certain things just in case. If there's a guide out there, a link would be nice

Should I save weapons with max familiarity for any reason? Will I be able to transfer any effects I want from any piece of gear? If anyone can give me a rundown on how everything works when everything is unlocked and how far into the game all the mechanics are unlocked, I'd appreciate it (without spoilers please).