Giant Sword Bug?

Hi there Just started out playing on this server when i obtained a Giant Sword+9+Skill+Opt 4 from a Heart

and was unable to use the Slash Skill that it had with it
i tested it out even tried switching weapons re-installing the client and all still nothing worked not a major problem tho since it seems to only be the giant sword any other weapon with +skill works fine as Mithrealis suggested ingame
it may be a client related issue

hoping for a swift answer

also including a pic to show that the Slash Skill really shows in red

 

You need atleast 20 energy