Hidden Saber

Some players considered this to be a godly weapon even better than the Akantor Katana which has +40% Affinity but has less than desirable sharpness, obtainable on 9* Cat-Elder Quest

You can easily get the materials in the 9* Cat-Elder Quest. Quest Name: Shadow of the Old Forest(1)"Which is also the urgent quest before you start the 9*quest" /Jungle Assassin(2)

Also If you plan on making this LS from scratch, it would be better for you to just upgrade the Tigrex Tooth. You need to catch it many times because the Naruga Marrow has only about 5-8% chance that you will receive in the reward.