Any magical 2h slash weapon.
 

I want to kill wisps, and have practiced 2h slashing. Need it to be magical~ Will pay anything near 50p... I have little money.

See if you can get yourself a tainted 2 handed bastard sword from kithicor from groups fighting there.

How can I get to kithicor from Qeynos?

Qeynos Hills > West Karana > North Karana > East Karana > Highpass > Kithicor

or

East Karana > Gorge of King Xorbb > Runnyeye > Misty Thicket > Rivervale > Kithicor