I'd actually consider this a 35% troll build; here's why...
Characteristics:
1) Silver Knight Shield has the best medium shield stability as far as I'm aware.
2) We all know the Silver Knight Spear is kind of an easy mode weapon considering how hard it is to punish.
Strategy:
1) Start off the duel with poison arrow spam. (Phantom hits with the poison are almost inescapable). This will put them more on an offensive play-style making them more likely to mess up.
2) Try to bait the opponent into bumper humping (My term for RB/R1 spam). Once noticed, try to second hit parry depending on what weapon they're using or if they're predictable; try a first hit parry. (If you're having trouble with quick weapons try watching jblackmel's "Parrying Insructions" videos).
3) If the opponent tries to backstab fish, you can counter-backstab with the Rapier for some decent damage.
Happy hunting...
Xbox GT: Auti the Swift