Homebrew Monk/ Assassin help

So, this is an idea for a new homebrew prestige class based on a holy/good mix of a monk and assassin.

I planned on including the AC improvement, the Fast movement progression of the monk, and the sneak attack and death attack abilities of the assassin. I am also considering giving a quarry like ability that improves the players death strike ability, as well as normal attacks. The only problem is that a monk that prestiges into assassin would have the same abilities, so what would you suggest as a unique ability solely for this class.

Note: I also added in a clause to the death attack that requires the player to take a standard action to atone for the kill. If it is not taken within ten rounds of the initial death attack then the assassin can not perform another one for at least twenty four hours.

Heres some flavor information if that helps:

All of the Monks(thats what I'll call them for now) are members of an Order. The order believed in a strong set of values that strictly governed their way of life, the Creed, which consisted of three tenets:
"Stay your blade from the flesh of an innocent."
"Hide in plain sight, be one with the crowd"
"Never compromise the Brotherhood."
These tenets permeated every aspect of the Assassins' daily life, as well as their fight for "peace in all things". The Assassins carried out their duties through political strategic assassination, in the hope that killing one individual, would lead to the salvation of thousands. The assassins believe that they fight on behalf of those who do not possess the abilities, resources, or knowledge to speak out against those who abuse their power.

The assassins spent their entire lifetime training to kill[1]. From an early age they were taught to observe their surroundings and plan ahead; combat was a must and its training was continuous, with a focus on bladed weapons of all sorts being their expertise. However, despite such a focus on combat, the greatest consideration in the assassins' training was concealment; stealth was the greatest weapon of the assassin and everything about their life, the clothes they wore, where the lived, even how they walked emphasised a devotion to concealment. It was the duty of an assassin to reach their target and stand beside them, before they struck, and sink away into the crowd.

The other significant focus of an assassins training was maneuverability. By the time an assassin reached the rank of Master Assassin, he was also a master of an early form of parkour widely utilised by the assassins. Widely seen as alien and naive by the general populous, this method of movement allowed the assassins to reach areas not normally accessible to man. From scaling a wall to climbing to one of a city's many view points, parkour gave the assassins a significant advantage over the average city guard.

This was taken from the Assassins Creed wikipedia page, if you have played the game, imagine something similar to that (without the hidden blade).

Sounds like assassins creed meets wanted.

but if it was to be a separate class (so that a good aligned player could join) what ability/ies could you add to make it stand out?

I'd just use the Inquisitor as a base class, throw in your monk stuff and a few death strikes, and trade out the Judgments. Maybe.

Have you checked out the Shadow Assassin class we released? It might be what you're looking for:

[PFRPG] The Genius Guide to the Shadow Assassin - OtherWorld Creations | EN World PDF Store

Hyrum.
Super Genius Games
"We err on the side of awesome."

That seems close to what I am looking for, I'll have to check it out. I did have one idea, so I might as well post it here, to see if there are balancing concerns.

Slow Fall: Player looses all Slow Fall abilities, and instead gains Sneak Attack (as rogue ability) at those levels.

*blank* body: player looses all of these abilities (purity of body etc.) in exchange for the death strike ability (as assassin ability). The ability is gained at fifth level, and can only be used while the player is unarmored, unencumbered, and is using only special monk weapons.

Upon reaching 9th level the player may spend 6 ki points to make a death attack without studying a target, or he may spend 3 ki points to make a death attack with only one round of study.

I tried to not make it as powerful as the assassin abilities, and there is still the issue of sneak attacking and flurry of blows (not sure how to sort that out), but I'm still worried it may not be balanced. Any feedback?

Upon reaching 13th level all death attacks are made with only one round of study, and three ki points may be made to take it without any study.