I have both Sheena and Samupi at 3rd jobs. Samupi is pretty good for me most of the game that I have played so far (chapter 21, I have spent the past week farming than advancing, FUCK ANIMATONS!). Sheena being a SS levels naturally slower but she does hit harder than him. They both get 2 giga attacks but I prefer Sheena's because the Samupi gigasword (cross) doesn't necessarily hit everyone within a pincer though it is useful if he was sandwiched himself, so it is still useful but not as useful if you want to pincer a long line of people. If you want to build Sheena full offense you can fill 4 of her slots with just attack skills. I still don't have any of her jobs at 65 though so I can't tell you how much conversion rite actually heals, I have read it is like leeching blade except it hits all, I hope it is good at offhealing.