Actually the damage bonus I'm talking about is not related to the proficiency or suit. It's a bonus of its own. The tests were conducted in isolated areas of the matches in three different matches to ensure consistency. PC battles would be inefficient for testing due to the resources required to start a PC battle just for a simple test. It was better to do it in the mercenary battles where we can choose separate sides. We did encounter one arrant merc messing with us, but thankfully he didn't skew the results.

Still never seen these supposed knifing skills ingame.

Alright, I set up a corp battle to try this today, with a team of SI on the other side, as test subjects.
The testing was extensive and I was using Proto Minnie scout and Proto knives.

Knives do 100% to shields and 100% to armour.
Knives do 150% to the head
A fully charged Proto knife does 600 damage per hit (+ your proficiency)

I also investigated the effectiveness of damping and passive scanning - WHICH DO NOT HAVE ANY EFFECT WHATSOEVER.
I'll be submitting a bug report including details of my tests later this week, maybe even tomorrow.
I've wasted 2mil sp on these skills at the minute.

We then played hide and seek, 'twas fun.

---Update 5 July 2013---

Holy crap, I just got finished with a match where I ended on the top three of the roster with 21 kills and 13 deaths as I was bringing hell upon the opposition that was gathering around B while they failed aimlessly trying to hack A in the Ashland map as I kept on picking at them (even their heavies and logis) one by one to keep them on their toes. It went on like this for literally 90% of the match until the end when suddenly we lost E and C. As a result we lost the match but not without putting up a damn good fight with my knives which probably explains why we were able to hold on for so long. I kept going at them bobbing and weaving 80% of their shots as I fillet their assaults and scouts. Even the heavies were starting to fear me. I guess I pissed them off because as soon as they saw me close to the end of the match, they all focused fire and completely surrounded me despite the fact that my friends were nearby. LOL

Then there was this other match which I believed to be Skim Junction with the communications outpost. When I got into the match, I realized I came in late and my team about about to get overrun inside the city. I decided to go into harassment mode and started causing all sorts of chaos between objectives A, B, and C since they were close together. A was the first I went to as I interrupted a hack being made by the enemy as I killed one dude but failed to killed the other next to him. By the time they resumed the hack it was too late as my team came in to finish the job. B proved to be quite the hotspot as I doing hit-n-run tactics with a combination of flanking moves to confuse the enemy. After clearing out B with the help of a random blueberry, I went to B to stop a shotgunner from hacking C and took out his spawn uplink which he foolishly left out in the open. I then proceeded to scout around the area surrounding the CRU by C and spotted two mercs trying to sneak in. One got taken out by a blueberry while the other got stabbed not sure what just happened. We won the match as a result. It's a good thing I came into the match just in time.