[Wrana]

Actually, Japanese fencing was more offense-oriented relative to both European and Chinese ones. So, it looks like their defense is quite OK. Regarding arrows, I think lack of shields is partly compensated by their own bows - which, of course, leaves you with more resource-intensive troops, but you can use them for both missile combat and shock attacks. Historically, Japanese army suffered greatly in missile combat both during Khubilai-khan's invasion and in their own invasion of Korea in 16th century...