Cloud wields a variety of weapons throughout his appearances. His most iconic weapon is the Buster Sword, a massive two-handed broadsword that he wields in Final Fantasy VII and most of his spin-off appearances.
In Advent Children Cloud has abandoned the Buster Sword and instead wields the Fusion Swords, a collection of six swords that can combine together into one, the individual swords having a variety of designs and their fused form being directly based on the Buster Sword. In Final Fantasy VII Cloud is able to equip katanas and other greatswords as well, though he continues to wield the Buster Sword in cutscenes.
Just look at the left picture,that is the sword he uses.