A way to easily defeat Ruby weapon with just Barret:
Have 8 Hero drinks, and loads of X-potions.
Barret
Missing Score
Wizard Bracelet
Ribbon
doublecut-speedplus counter-mime counter-mime counter-mime
counter-mime counter-mime counter-mime counter-mime
At the start Barret can use a hero drink, then wait for the Ruby weapon to do something, and Barret will counter by using 7 hero drinks. Then Barret can use "4xCut" and wait, when Barret counters again, Barret will do "4xcut" 7 times (each can be close to 9999 thanks to the hero drinks). So that's almost 280,000 in just one counter. Then just wait so Barret can counter again. After the second time Barret may need to use an X-potion. Then Barret can use "4xcut again", and wait to counter.