gem weapons swap x and y

Should be self describing.
But yeah in weapons stack to swap to items in place.
I want to keep my entities setup close by:
1 2 for fire
3 4 for earth
etc
Sure some might be reusable, but if I get new shield for earth there is either
use 3 8 or purge 4-7? But 4-7 might be too good items to purge.

Thank you in advance