This is THE standard Ninja build that the ninja clan recommends to new members:
Lvl30
Strength: 15
Agility: 24
Skills to attributes: 8
Ironflesh 0
Power Strike: 5
Athletics: 8
Weapon Master: 8
Two Handed: 173
You get 2 surplus skillpoints which you can put wherever you like. 2pt, Throwing daggers and around 100 wpf in throwing is not a bad idea.
Consider this the minimum amount of powerstrike to be effective with a stock katana. With a MW katana, you could go 12-27 even because of the extra base damage.
* Use your speed to pick the fights YOU want and you can win.
* Always bring a throwaway bamboo spear when moving alone in the open. Aim for horsehead, when stopped immediately switch to katana, block the horse with your body and take it down.
* Your melee skills must be good
* Try to use your brain in stead of melee skills.
* Aim for heads
Personally I like my hybrid thrower because of lots of flexibility. I do sacrifice a lot of speed and 2h wpf to make it work though. You can't spam anyone with my build. The idea is that 3 jarids replace bamboo spear for cav deterrent. I also carry 8 mw snowflakes to scare/headshot archers, prevent xbowers from reloading.
Also, lvl 33
Level 33 (35 569 612 xp)
Strength: 18
Agility: 24
Skills to attributes: 8
Power Strike: 6
Athletics: 7
Power Throw: 6
Weapon Master: 7
Two Handed: 122
Throwing: 133
(The build is complete at lvl 34 around 80million XP though. It also has a 15/24 sweetspot at 31 so this is if you dont plan to retire. Also, all weapons and most armor masterworked.. lvl 34 is like 10 generations so for average player with not many masterworks, better wait a bit. On the other hand, pure ninja is a money saving playstyle, so you might be able to buy some loompoints after a good while. If you take a hybrid Ninja like me, you make much less.)