rajang S is the high rank armor right? If that's the case , change your armor to G. one. You are at second rank of G.rank quests , I guess it will be quite hard with High rank armor....
Also remember that if you break the shogun's (normal or terra) claw/pincer , it will be on rage mode for the rest of the quest. Terra shogun has weak pincers and hard shell and normal shogun has strong pincers and weak shell.