Assassin styled rogue advice needed please

[Stalarious]

As the title line suggests I'm looking to build an unchained rogue that specializes and sneak attacks. While now the while not out of the ordinary I am looking at building him around using knives and rope dart. This is because I really like those two weapons in Assassin's Creed I am in a campaign that allows for A 25 point purchase on abilities. My end goal would be to have him stay unchained rogue only any advice or tips are greatly appreciated

[Imbicatus]

First off, I would recommend against the rope dart. It's a generally terrible weapon and you would be wasting a feat on it for proficiency.

Unchained rogue is compatible with archetypes, so You may want to take knifemaster for access to d8 sneak attacks. River Rat trait for +1 to damage with daggers is great. If you worship Pharasma, you can take deific obediance for +2 to hit with daggers as well. This will let you offset the TWF penalty, and Two Weapon Feint is golden for rogues.

[xDemoquinx]

You could take a lvl or so of unchained monk to get prof. I like the kyoketsu shoge better than rope dart. Could model him after Scorpion from Mortal Kombat, if you wanted. Hamalatsu Strike with some grapple feats and the strangler feat to apply sneaks on grapple checks.