"sell back" option to get out of the current problem of limited inventory

we should be able to sell back legacy items for coins(of course i don’t expect tacticsoft to give us tokens for them) or ultra powerkits.
further it is more sensible to use powerkits to upgrade a weapon.
i never got the idea of how to fuse weapons into another ; do you melt those weapons and put it into others.
specialized powerkits(heat,energy,physical, etc) would be good

You take away good parts of a item and put those into

And Power Kits are a Mystery like Mohadib 's Helmet