Brock Savage wrote:

I am designing an ancestral sword for my player's Hyperborean warlock and feel like my write up is uninspired and boring. It needs more of that weird fantasy flavor. Ideally I'd love to see it generate an adventure or two. It also needs a name. Drawbacks and flaws are totally cool but bear in mind that House Vheez would have tossed it in the ocean if it was too problematic.

Here's what I have so far. I welcome feedback, criticism, and advice.  

A rune-etched longsword forged of starmetal, this ensorcelled blade has served House Vheez for millennia. A nihilistic alien intelligence is trapped inside this weapon; its primary desire is to devour souls and bring entropy. When the bearer reduces a creature to 0 hp the weapon consumes their soul, utterly destroying it. This weapon serves as a sorcerous focus and is considered magical against otherworldly beings; its runes glow green in their presence. On a natural 20 the weapon deals extra damage to living foes (not undead, robots, constructs etc.) and grants the bearer the same amount of temporary hit points. The sword occasionally offers to reveal secrets and teach spells to get what it wants (more souls). Conversely, it grows furious if it hasn't eaten a soul in a few days; after a month the alien intelligence goes into torpor and the weapon loses all magical properties until it consumes a notable otherworldly soul. Alignment is Chaotic.

         I would advise but my thoughts pale compared to what you have already accomplished here....
Generally "magic" or "sentient" weapons (for me)  are those that have been used over many generations and have begun to adopt power from the souls they have taken and the personality of the people / families that have wielded them.
       I have a convention character that wields a "Sword of the Ancestors" that has grown in power over time as generations have passed and lives have been taken.  They aren't created with great power but evolve over time into weapons of renown. They begin as mundane weapons and are used by great warriors with powerful souls to slay powerful people / beings. The nature of Hyperborea allows part of the energy to be retained in the weapon.

I don't find the description boring at all and like what you have done.
 

mabon5127 wrote:

Generally "magic" or "sentient" weapons (for me)  are those that have been used over many generations and have begun to adopt power from the souls they have taken and the personality of the people / families that have wielded them.

They aren't created with great power but evolve over time into weapons of renown. They begin as mundane weapons and are used by great warriors with powerful souls to slay powerful people / beings. The nature of Hyperborea allows part of the energy to be retained in the weapon. 

Thank you for the kind words. You input is exactly the sort of thing I was looking for. I want a comparatively weak but flavorful weapon that evolves into a mighty blade when wielded by a strong soul (high level) who frequently feeds it other strong souls.

I want the player to feel constant  pressure to feed this thing. At first the being isn't too picky but it grows more demanding as its power increases. I'm unsure how I will scale this hunger or what leverage the blade will exercise over the wielder.

gizmomathboy wrote:

I think if you want the weapon to scale, it should be found in a depleted state. The Green Death is an excellent reason it hasn't been wielded in generations by a member of the House. 

The player owns the weapon but the alien within is dormant. I imagine a combination of the Green Death and dynastic tragedy led to the weapon being shelved for centuries.
. 

gizmomathboy wrote:

Definitely think about how the sword will just have a desire to eat a soul in that state and might not be able to control a character other than to feed. As it gets "stronger" it might be more sentient and start directing it's desires and goals.

This is a good guideline, thank you.