I have yet to see one and I'm wondering if there's a list of all the combinations possible. I don't know much about PSO past what I learned on gamecube. I only really know you can combine Sange & Yasha. Noob needs help xD.
I combined a Yasha and Sange the other day and it took on both percentages Sange with 40% hit Yasha with 20% Machine and 20% Beast Sange & Yasha with 40% hit 20% Machine 20% Beast.