What is the strongest keyblade in Kingdom of Hearts 2

there are two,the ultima weapon and the ferir
ultima- sinthesis
ferir-i dont have it but i think you have to beat sepheroph (or however you spell his name) then you go talk to cloud then something-something something......
HEY this would help way more than me, go on youtube type in what ever you want to know and BAMMMM hey-presto theres your answer
hope i helped
ultraquestioner

Maurice Barnett's edit:
It depends what you are looking for. Me personally, I want the most strength so I would get the Fenrir. This is how: You talk to Sephiroth and then you initiate a fight with him. After you do this, you talk to Cloud and then go to Sephiroth and talk to him again. After the cutscene, Tifa will give you the Fenrir which has 7 strength and 1 magic ;)