where can i obtain s grade weapon recipes? i can't see their drop on the drop and spoil =|

They are obtainable from quests...
http://lineage2.stratics.com/content/library/quests/

lvl of the quest plz...

Forge of Gods or Imperial Tomb.
IT - Random recipe
FOG - Random or selectable recipe - depends on place (npc) that u ent the Quest.

in both FoG and IT u can chose recipe or take random.
in FoG (the quest "Gather the Flames") there are 2 NPCs. 1 that gives the quest and from which u exchange 1000 torches for a random recipe (Blacksmith Vulcan) and another NPC that moves like Master Toma but in FoG from which u can chose a recipe for 1200 torches (Blacksmith Rooney).
in IT there are 2 quests: Relics of the old empire - from this quest u earn broken relics and u can exchange them for a random recipe (1000 relics each); and the 2nd quest: Four Goblets (in the Four Sepulchers) - u can safe the relics from the other quest (Relics of the old empire) and by passing 5 rooms with insane mobs and killing the raid boss in the 6th room u will be able to teleport to the Temple of Piligrims where u can exchange for 1000 relics per recipe of you choice but the quest Four Goblets is really difficult and max 1 party can enter at a time.