I'm gonna go with a +3 Great Bardiche for two handers. HUGE cut damage. Bonus against shields, solid animations. Pretty cheap upkeep, good range. All around goo weapon. Crazy ghost reach.
Also Goendong weapon thing. Knock down, blunt, AND a pierce thrust? Swing range goes off the tip of the spike at the end giving it some of the best ghost reach in the game. If not THE best. Not to mention very solid, but WEIRD animations make it hard to follow!
That being said I'm trading both of those items on the market place. Bardiche + gold for steel bolts. Goendong + gold for italian sword.
WHAT DO YOU ALL THINK IS MOST UNDERRATED WEAPON?