uppercut on dual blades can't be cancelled with weapon swaps or sheath. however, you can jump, so the way to weapon swap becomes jump > weapon swap.

similar the other weapon swap into greatsword combos, this does a lot of damage, more consistently and with less effort than single weapon combos.

jump then weapon swap then attack, but quickly ! can horizontal attack while weapon swapping can vary timing of jump

shout out to kipac who shared this with me from a c7sper video (linked at the end)