what would happen if you turned yourself in for a crime you INTENDED to commit (with proof) but never carried out?

what would happen if you turned yourself in WITH EVIDENCE. like you go to a police station and say something like "i wanted to assault someone but i decided not to. here's the weapons" and surrender them, assuming the weapons are legal to own. my best guess was they could do some sort of psychiatric evaluation but is there anything beyond that?

i imagine if the weapons are illegal they can charge you with something related to that but i don't know about when it's legal (if it's a country where you need a license for the weapon for you carried you could get it revoked? idk)

i don't really care what country/etc is used as an example, i looked for posts on the same topic but i couldn't find anything exactly like this

also would it change depending on what you said you wanted to do? if you get a psych evaluation i assume they'd note it down the weapon, and what you specifically wanted to do with said weapons, because that gives them a different insight

sorry this got more deranged the more i wrote