Be nice. Anything between 2.5 & 6" is reasonable. If thats the size, shape, balance and heft your happy with then go with it. Your only real considerations are strength , grip, ease of sharpening & how easy is it to clean. How important each of those factors is of course a personal choice. As for the sensi, try a shotgun... ( there speaks a true descenant of the English Bowman). No, seriously , if your interested in that sort of thing, take a look at what happened to the samurai at the end of the 19th Century.