I know I'm a bit late to all this but I thought I'd say that I've played a high might/low fists character and it can be a really rewarding (and hilarious) experience (if anyone's interested it was a scion party-boy dilettante with inhuman strength/claws and a fair or average fists). I think anything that would have increased the character's accuracy on a regular basis (like a flat ruling that might always modifies fists) would have actually taken away from that character. However it seems like that flat ruling is no longer a prevailing opinion, if it ever was.
As a side note W&M, by a literal reading of the RAW blocks are only capable of preventing specific actions (read the paragraph beneath the bulleted list on YS210) and a defense roll is technically not an action but a part of someone else's attack (read the first few paragraphs of attacks on YS200). By this very literal reading of the book one could come to the conclusion that it is impossible to use a block to interfere with a defense roll. But I guess we all interpret things differently.
