Currently the weapon perk build is shared between classes and weapon versions, so if I build a combat knife in a specific way (block version with shadow stab perk for extreme damage) for a specific class (like Sniper to add the cloak damage bonus) then I'm forced to have the same build for the combat knife for the Vanguard, even if I take a different version

Same with class perk builds, for example if I use a Multi-Melta for heavy I may need to redo my build for Heavy Bolter or Heavy Plasma Incinerator, since there are perks that simply DO NOT work with other weapons. This also means changing loadout mid mission becomes an issue