First of all, I would like to mention that these tactics are made by me, and are my own playing style. Any faults can be mentioned, but not like that: NO THAT"S BULLSHIT NAAB.
First of all. You won't have a problem leveling from 1-80, as one of duelist's advantages is his great PvE ability. You can carry with you a sword, or a blunt, till you get your dual swords. Remember to use War Cry and Battle Roar
PvP tactics:
Duelist vs Mage: You have to have your Battle Roar, Lionheart, and War Cry activated, and if he is more lvls than you, accuracy, and vicious stance. First use Triple Slash, to frustrate him, then spam Sonic rage and then Triple Sonic Slash, and Sonic Blaster. Due to his low p def, he won't be so hard. Be careful of his curses. Try to interupt him, especially when casting anchor or curse of doom.
Duelist vs Archer: Not a hard fight. Try to keep close to him, don't let him escape with dash, but if he does, use your sonic move and get him. Remember your self buffs, especially Lionheart to prevent stuns
Duelist vs Dagger: Exactly like the archer, but be careful, use Sonic Barrier if he keeps consuming your hp, in case of emergency.
Duelist vs Tank. It's a bit hard here. Try to avoid his shield stuns and get away when he uses ultimate defence, and spam Sonic Rage and Blaster until he dies.
Duelist vs OL Interupt him! That's all you can do! His p def is great and his curses will own you. Try to interupt him as much as you can.
Duelist vs Duelist: This fight depends on your playing ablility and his style.
Sets:
1-20 -> Dream Set+ Blunt or Sword and Shield (Prolly Dream Sword and Skull Shield)
20-40 ->Anything Top, Search Giran shop. (You can use duals, if you have a set, otherwise blunt or sword+shield)
40-52-> Full Plate for me is fine, plus duals.Duals are now necessary, cause you have some dual only skills
52-61-> Blue Wolf Heavy and Samurai+Samurai
61-76->Tallum Heavy and Kesh-Kesh or Tallum-Dama or Dama-Dama
76-80->IC and Tallum Blade-DLE
-NotAbastard
-P.S I would like to add that if you have infinity duals with SA silence, you are the best, cause then mages won't have a chance against ya