not that hard at all. Unlocking all the weapon traits is not part of the platinum (even though it should IMO). The hardest is finding all the cryptic messages, xenoglyph cyphers, and all the logs i think.
If you want a personal accomplishment then unlocking all the weapon traits is the ultimate accomplishments IMO. But that will require a LOT of runs. There used to be a cheese in biome 6 where the containment room would re-activate if you left the room and re-entered. So with the right perks to re-heal yourself you could farm the room, the weapons and all the perks. But they patched it. But that was fun as hell. I'd have 40+ weapons lying haphazardly everywhere. Or i'd move them out of the room and stack them. Crashed the game once or twice from having so many weapons around.
PS. Ah i remember how i used to mass level up the weapon perks. In biome 6, make sure don't have any shield breaking abilities and just farm the the little octopuses (or whatever) that spawn from those giant pods. Find one that are shielded so you aren't worried about killing them and just keep on killing those little shits till you level up your weapon perks.. ALL OF THEM!