Scarlett will be able to get The Holy Spear of Chiefs as a reward after finishing her battle with Princess Chiamaka in the Necropolis of the Juma Tribal Lands. She'll find it in the chest in Tree of Life once she gets key from Princess Chiamaka. (The Pincess's Ring of Life will be found in the same chest.)
This Spear can be sold for 1200 ducats. It is a one-of-a-kind item.