Ancestral weapons make your moves much stronger and your journey to Eos much easier. These ancestral weapons can be found in tombs scattered around the Final Fantasy map. Some of these weapons will be part of your main quest while other can be effectively used against stronger enemies. Here is an FFXV guide to lead you to all the tombs and all the ancestral weapons you need.
Tomb of the Wise
To locate this tomb, head north to the Three Valleys and locate the tomb. Once inside, use the Power of the Kings to locate all the tombs and the Sword of the Wise.
Tomb of the Conqueror
It's on the east of the Tomb of the Wise at the very end of the Keycatrich Trench dungeon. You will find the Axe of the Conqueror inside it.
Tomb of the Tall
Go to Fallgrove, Duscae and defeat the monster near the dungeon called Costlemark Dungeon. After defeating it, you can retrieve the Greatsword of the Tall.
Tomb of the Wanderer
You will find this tomb when you do the Sword in the Waterfall quest. The tomb is located west of an icy region where the Sword of the Wanderer lies.
Tomb of the Mystic
To get your hands on the Blade of the Mystic, you need to find the tomb that hides it. All you have to do is complete the Archaean quest and go straight in an alleyway to find the tomb.
Tomb of the Fierce
The dungeon where the tomb is can be found by heading over to the southwest edge of Cieigne. There, the Mace of the Fierce will be waiting for you.
Tomb of the Pious and Tomb of the Clever
The Tomb of the Pious is located at the Malmalam Thicket dungeon while the Tomb of the Clever is in the Malouve Mines dungeon near the Galdin Quay.
Tomb of the Rogue
Find the Myrlwood dungeon which is on the south of Vesperpool. You will be able to acquire the Star of the Rogue there without any difficulty.
Tomb of the Just
Go straight to Tommels Glade near the west of the Disc. Search the area for the Shield of the Just.
Tomb of the Warrior
Last on this FFXV guide is the Tomb of the Warrior which can be found after you finish the Hand of the King quest. You have to fight a difficult battle here but once you won, the Katana of the Warrior is yours for the taking.