um..
While leveling my ninja I evaded/parried quite a bit on anything I was exping on that was VT-Low IT. In some of my parties, I could honestly get up and go get a cup of coffee mid fight. I would just slow/blind/paralyze and after that I could literally tank with Ichi.. even with DD gear on. I chose to use byrnie+1 at the time and stacked my ACC elsewhere for DD set up, so I had no negative evasion. Plus I had full evasion merits and my parrying was capped, so I guess that helped.
As for Haubergeon vs Osode for DD
Haubergeon
5 Str 5 Dex
12.5 att
12.5 acc
Osode
10 Str 10 Dex
5 att
5 acc
STR needs attack to back it up or its worthless. Unfortunately, Attack is something ninjas lack alot of. Any 1H weapons generally need ATT over STR. ACC is another factor, as if you miss alot, all the STR and even ATT doesnt add up for missed hits. Thats why Haubergeon or Shura Togi wins for Ninja DD, especially at 75 when the osode becomes available.
Osode is a much more roundabout piece, and helps in many other departments, giving a little benefit to each area.. but as a ninja, you are better off enhancing your DD capacity(ACC and ATT) in almost any party situation.