in KhII whats the best place to lvl??

[Roxas's Oblivion]

Thx for reading. i want to also know how to get soras strongest wepon.

[Tavrobel]

Ultima Weapon is Synthesized by collection of certain ingredients.
Fenrir is obtained by defeating Sephiroth in Hollow Bastion.

Ultima Weapon requires:
Ultimate Recipe (Twilight Town: Basement Corridor)

UW: Orichalcum+ x13 (7, events only)
Seal 100 Acre Wood
Seal Atlantica
Goddess of Fate cup, Olympus Coliseum
Twilight Town: Sunset Terrace
World that Never Was: Brink of Despair
Space Paranoids: Central Computer Mesa

UW: Orichalcum x1 (dropped by Bulky Vendors)

UW: Mythril Crystal x1 (Synthesized)
Mythril Crystal requires:
Dense Gem x3
Dense Crystal x1
Twilight Gem x3
Twilight Crystal x1
Serenity Stone x1
Dense Gems dropped by Samurai
Twilight Gems dropped by Assassins
Serentity Stones dropped by Crimson Jazz, Devastator, Living Bone, Morning Star, Dusk

UW: Dense Crystal x1 (dropped by Berserkers)
UW: Twilight Crystal x1 (dropped by Sorcerors)
UW: Bright Crystal x1 (dropped by Air Pirate, Crescendo, Neoshadow, Strafer)

The best place to level at the end of the game (or levels above 40) is WtNW. Otherwise, simply fight enemies at the areas whose battle level is closest to your current level.