Well, we don't want you to be uncomfortable.
So what are we adding to
The Reaper Working Draft?
For AC the latest version is:
Armor Class: 21 (+4 Dex, +2 insight, +5 natural), touch 16, flat-footed 17
With the insight bonus needing to be mentioned somewhere, I'm thinking we should put it in Masterful Combat Reflexes.
Masterful Combat Reflexes (Ex): The Reaper adds its Wisdom bonus to its Armor Class and to the number of attacks of opportunity it can make in a round. It also has good Reflex saves.
Although we could add it to Martial Training:
Masterful Combat Reflexes (Ex): The Reaper adds its Wisdom bonus to the number of attacks of opportunity it can make in a round. It also has good Reflex saves.
Martial Training (Ex): The reaper was a master martial artist in life, and retains the martial skills it once possessed. The reaper possesses the base attack bonus of a fighter of a level equal to its Hit Dice, and qualifies for fighter feats as if its Hit Dice were fighter levels. It is proficient with all simple and martial weapons and with all armor (heavy, medium, and light) and shields (including tower shields). Furthermore, it gains an insight bonus to AC equal to its Wisdom bonus.
Shall we cut the armour proficiencies, since AD&D Kensai aren't skilled in armour and The Reaper doesn't wear any?
Martial Training (Ex): The reaper was a master martial artist in life, and retains the martial skills it once possessed. The reaper possesses the base attack bonus of a fighter of a level equal to its Hit Dice, and qualifies for fighter feats as if its Hit Dice were fighter levels. It is proficient with all simple and martial weapons and gains an insight bonus to AC equal to its Wisdom bonus.
You also suggested Intimidate in the working draft, and we can max out 5 skills. How about Intimidate 12, Jump 12, Listen 12, Spot 12, Tumble 12? Or something similar?
That would seem to cover everything it needs.
We still have a few special abilities to sort out though - Rejuvenation and Sword Charm. Those are tied together, and should be the same for all the Seven Swords.