Intelligence in DkS consist in:
-preparing the best build around a weapon, with specific poise values, min/max stats, decent HP and creativeness.
-knowledge of your weapon's moveset, and how to properly use it in the battlefield (ie. useless R2s and good weapon combos).
-knowledge of all weapons poise break points.
-knowledge of all weapons weaknesses and strengths (ie. bow vs spear).
-predictiveness of your opponent's moves and how he uses the weapon.
-knowledge of various PvP techniques, and how to counter them by simple attacks/dodges. You don't need to rely on PvP techniques to win, but the simple use of counters can save you from losing. (ie. dependence on roll bs vs counter bs)
-get used to DkS's PvP lag so you can predict your opponent better (ie. counter bs, spears phantom hits).
-control the fight, "he who controls the fight wins the game". (quoted by my friend Forum Pirate)
-knowledge of all PvP techniques. Mostly learned by watching youtube and practicing everyday. A must have for any skillful player.
-reliance on random attacks and parries. Luck is an important part of DkS due to lag.
-reliance on fast roll/DWGR to dodge every single attack with super reflexes.
-can fight without lock on, especially with pyromancy.
-Usually favored by Dex weapons, it's easier to to be skillful and win with fast attacks
These are only a few, if you have more be sure to post them and comment on these. Personally, I only use counter backstab and toggle escape to survive with maybe a bit of unlock to throw fireballs, but other than that my fighting style is pretty simple and I don't use techniques.