Hades - How to unlock hidden Weapon Aspects

To start upgrading your weapons, you will have to unlock all weapons first (they are called Inferal Arms, and upgrades are called Aspects). The next time you die, you will be informed about spending Titan Blood on them to upgrade them. Simply equip the weapon and again press the R1 button to enter the upgrade tree. Hidden weapon Aspect is the last 4th upgrade on the list.

Unlock the first, second and the third one to use them, and for the last one, there are some pre-requisites:

• Unlocked at least 5 Aspects on weapons other than the Aspect of Zagreus, which is the first weapon aspect on all weapons (for each weapon!)
• Unlocked the "Fated List of Minor Prophecies" Work Order
• Reached the final boss (the one behing the Cerberus in the 4th area)
• Spoken with Achilles in the House (your hub area where you respawn) until he mention the hidden weapon aspects. He will also give you the unlock phrase for Eternal Spear weapon.
• Interacted with the Eternal Spear to unlock the Aspect of Guan Yu hidden aspect

To unlock the hidden aspects of remaining weapons, you need to spend at least 5 Titan Blood invested in their other Aspects before you can unlock the hidden one, just so you are aware. Do that first, then work on the tasks below.

Stygian Blade

After completing the above requirements, speak to Nyx until she give you the phrase "I see your kingly pardon from a prison of stone". Approach the weapon to unlock its hidden aspect.

Heart-Seeking Bow

After completing the above requirements, keep talking to Artemis (during your runs pick up her boons), until she give you the phrase "I see you drawn in the arms of the seventh avatar". Approach the weapon to unlock its hidden aspect.

Shield of Chaos

After completing the above requirements, keep talking to Chaos (during your runs pick up his boons, he is in the black hole that can appear on the floor after you unlock him from the Work Orders), until he give you the phrase "I see you stand your ground against the serpent’s flame". Approach the weapon to unlock its hidden aspect.

Twin-Fists of Malphon

After completing the above requirements, you need to encounter the minotaur boss (Asterius) before the actual fight with him and the other God at the end of the 3rd area. This can be tricky, but the trick is to always select the doors with the skull icon; one of the doors with lead to fight with only Asterius. You need to reach that point while wearing the Twin-Fists weapon, and you have to do it at least twice until he give you the phrase "I see you overcome the wild and make peace with death". Approach the weapon to unlock its hidden aspect.

Adamant Rail

After completing the above requirements, keep talking to Zeus (during your runs pick up his boons), until he give you the phrase "I see your prideful fall down from the heaves to the flames". Approach the weapon to unlock its hidden aspect.