Lets say you have a piece of armor or a weapon and you level it up but don't particularly like the available perks on it and you want to change it to something you think would be better suited for your play style. Like a chestplate that gives you bonus ammo for auto rifles but you prefer using scout rifles or hand cannons, If you find another weaker piece of gear with the preferred perk on it for scout rifles or handcannons you can simply go to the speaker if its armor and delete the perk off the stronger piece and replace it with the perk from the weaker armor while also dismantling the weaker set, for motes of light. Same with weapons instead you'd go to the gunsmith and pay motes of light or glimmer. Some restrictions would be it would have to be from the same class of weapon or armor(scout rifles for scout rifle perks, autorifles for autorigles, chestpieces to chestpieces, etc) / character class specific (if your a titan it has to be a piece of titan gear)