Pick Which Gear Gains Heat

How about an option on weapons and gear to pick which items gains heat and which do not.
I think he means that he wants the ability to power level up a certain item. If you have all lets say 5* gear and you want to boost up a sealed sword, you can give all the heat from that level to the sword and just not give any to your other gear.
This is already in the game.
It's called "equip only one thing that can be leveled."
Because clearly everything else we own is already Level 10.

If many of you have attempted at some point in Sk Lives to train your helm, shield, armor, and two weapons at once (Or even more due to slots) it takes A LONG TIME, and then you find out 1 item training is SO MUCH EASIER. So, have an option to train one item at a time you pick the item, and this allows players who dont have all level 10 gear to train up their gear so much faster.
@Magnus - most of my gear is completed, but now we have to re-do everything we trained it would be easier to 1 item train that 20 item train.
Then just max out your 0-star gear like a champ.
What is your goal? To have one weapon gain more heat at the expense of another, or to have a weapon that does not gain heat to stay at a low level?