“by” vs. “of”

The usage of "possessed" in this context still sounds strange to me. I'm not sure you can "possess" personality traits like integrity or loyalty.

And take a look:
http://www.wsu.edu/~brians/errors/possessed.html

My 2 cents: I would just say "...and to always be trustworthy, loyal, honest and committed..."

In agreement with Ed, "possess" sounds strange to me, too...I think "has" is a more common usage with those kinds of traits.

Of course you can possess integrity or loyalty.. That's absolutely correct. Whether you can be "possessed of" them is a little different; strictly speaking you can (it's not absolutely wrong), but as Ed and CQ point out, it sounds strange to the average modern speaker.

You still sometimes see it used in a wry sort of way, though, for instance: "As Mark walked out of his drunk girlfriend's apartment, he slyly possessed himself of her car keys so she wouldn't be able to drive that night." Or, Mom's favorite, "You can't just walk up and possess yourself of anything in the fridge."

Note the use of "himself," "yourself," etc.

The last serious use I saw of this construction was in a Victorian-era novel, in which the hero had befriended a man in trouble, who later turned out to have been a nobleman; upon that nobleman's death, our hero suddenly "found himself possessed of the old gentleman's entire legacy."

this probably depends on the job, I quite like the way it sounds, and it could be that your employer has a fondness for dickensian phrasing, however you don't want to sound pretentious as that can really put people's backs up, so judge your audience; but to answer your original question I'd definately say "to be possessed of integrity..." rather than "possessed by", that sounds a bit scary ;)

Of couse it is of, not by. You're the one who possesses the qualities. The qualities aren't possessing YOU. Unless, like Charlie says, it's something scary, like in the amityville horror or something.