I can't even imagine how it'd feel to get my side torn open. It must hurt a lot more than crushing of the rib bones, so...
Anyway, if you don't buy my explanation, blame the curse.
Tenshi, you must be referring to Kogamitsu's kunais (I remember mentioning my nick is a rip-off from her name :satisfied). They originally had Finnish names; "Valon jumala" and "Pimeyden jumala", meaning the gods of Light and Darkness. I just tried hastly translating them in Japanese.
About Yoshi being skinny - well, I can't help it much. Bryan keeps wondering many things I (and Jyri, the muse of the Blood Ring) wonder about Yoshimitsu, too. In some pics he looks definitely an anorexic, especially when trying to count out the armory around his waist.