[Memorylight]

I got it on disk 3, don't remember how, but most of the items to all the best weapons in FF VIII I got from playing cards then using Quetzacolts card ability into changing them into rare items. And when you get Rangerook, fly to an island called The Island Closest to Hell. (should be an Island close to the Galbadia Island)
There are a lot of hard-to-beat-monsters but they all have rare items if you defeat them.
Lionhearth is a good weapon but nothing special, but of course, if Squall has it he can do his fantastic limit break Lion heart and wohooooo, it's so totally worth it! Also try getting Irvines best shot gun! He is amazing in his limitbreak if you have AP or Pulse ammo. When the Lunar cry happens (disk 3) you'll find a guy laughing when you talk to him and he'll change into this big bird monster thing, use mug on him and you get Energy Crystals (or something like that) and use Ifrits ammo ability into changing this item into pulse ammo, (or maybe AP ammo????) Anyway, the guy always come back so I fought him like a hundred times and got a lot of Pulse/AP ammo thanks to him! You can easily beat him by junctioning death into you attack slot.
And I assume you've already found the weapon issue in Odins laboratory with all the "ingredients " of making some of the characters greatest weapons (including Lion Hearth).
Hope this is some sort of help for you, my English is not my mother tongue so I don’t blame you if you don’t get any of this. ^_^

And by the way, the laughing guy is just sitting on the railing in Easter city, just talk to everyone you meat and when he says "Hahahahahahah" then you know it's the right guy. Sorry that I cant give you some closer info on where to find him....

EDIT: Please don't double post. Use the edit button instead. -Murder