I have an issue of being a bit of a control freak with my character's backstories and it gives me the issue of I have so much planned out there's no room for surprise and I get bored. So I had an idea to do something different for my hexblade. The character has no memory before the age of 13-16 (haven't decided) but has a shard of black metal she hears a voice from (her patron) who teaches her how to get by in the world and becomes a sort of guardian she's dependant on. She meets a member of an organization in the setting and uses those fancy new warlock powers to become a faction agent and is particularly loyal to the member who brought her into the fold. Basically her main goal is finding the missing shards of the weapon her patron is bound to and serve the faction she's apart of allowing the DM to tie the earlier parts of her life in as storyhooks for the party as needed. Does this sound reasonable? Or does it fall into the same category of eyeroll and groans like most amnesia stories?
Not remembering what happened prior to 13-16 isn't that big of a deal I would think as most adults don't remember much prior to that age range normally. However I'd presume the "amnesia" occurred during the time the character discovered the shard or soon after which would lead me to believe (if I was in the characters shoes) that the shard may of in some way be connected to my amnesia, making the journey to recover more shards not just be about completing the weapon the patron is attached to but potentially unlocking lost memories and/or possibly discovering the reason behind my amnesia.
So I don't think that the amnesia will be much of an issue but I do see one potential issue. And that is that your character essentially is on the path of a "chosen one" style character. Meaning that the various adventures your party goes on in some way could be connected with your character's development, with your DM not only making your past part of story hooks but also the completion of your patron's weapon apart of the journey. Potentially rubbing other players the wrong way, since things could primarily be about your character and not their own. Therefore I'd hope your DM have the foresight to explain all this to the group before proceeding and make sure they are on board with such. And to help in that regard, two good examples of this working is Avatar: The Last Airbender if your DM chooses to make you a central focal point or how Keyleth was treated with her Aramenté on Critical Role if your DM chooses to make your characters personal quest more a side quest for the group that is done at their leisure. Also, I'd look to the character of Kagome from Inuyasha as she very much has the "chosen one" thing going on and is looking to collect shards to complete an artifact very much like your character. Which makes using her as an example actually quite perfect, assuming some bit of her wasn't already a source of inspiration for your character considering the strong similarities between the two.
Finally on the above point of Kagome's mission to collect the shards of the Shikon Jewel, if I was your DM I'd definitely consider that others would be seeking (or finding) the shards of your patron's weapon. Leading to all sorts of issues as seen with those who sought or accidentally came across the shards of the Shikon Jewel. Plus there is to consider just how your patron's weapon comes together, does it come together automatically? Is a special ritual required? Does it need to be smithed in a special place? And then what happens when it's complete? Does handling your patron become like any other sentient weapon or something more? Do they ask you to perform a special ritual to free them from the weapon and if you comply then what? Do they turn against you and your party resulting in an epic boss battle? Seeking your magic power and life out of necessity (to finalize their resurrection) or simply out of greed for more power. Leading to your character potentially having to sacrifice their power (if not their life) to end your patron. Or are they grateful and bestow upon you a boon of some sort?
And since these came to mind while finishing up, here are some other sources of inspiration:
Shendu from Jackie Chan Adventures - The whole goal of the first season was Shendu becoming complete by finding twelve Talismans. With Shendu and the talismans easily being a good stand-in for your patron and its weapon shards.
Malchior from Teen Titans - As Raven is tricked by Malchior in the show, so to your character could be tricked into unleashing a horrible evil upon the land.
Demon Blades from Inuyasha - Any of these demon blades could serve as examples of how your patron and the weapon they are bound to may act and/or your patron's origins.
Sentient Weapons in Other Fiction - Alternatively to the above, you can look to well-known examples of sentient weapons such as: Frostmourne, the Sword of Omens and the Master Sword. But if rather look to D&D for guidance, there is Blackrazor, Moonblades and Singing Swords (such as the funny and annoying Lilarcor). Of course, this is mostly useful for when the weapon is complete but it's always good for you and your DM to know where things can be going ahead of time. And if you need even more examples for such, TV Tropes is great for this sort of thing with entries like: Empathic Weapon, Evil Weapon, and Talking Weapon.
I have an issue of being a bit of a control freak with my character's backstories and it gives me the issue of I have so much planned out there's no room for surprise and I get bored. So I had an idea to do something different for my hexblade. The character has no memory before the age of 13-16 (haven't decided) but has a shard of black metal she hears a voice from (her patron) who teaches her how to get by in the world and becomes a sort of guardian she's dependant on. She meets a member of an organization in the setting and uses those fancy new warlock powers to become a faction agent and is particularly loyal to the member who brought her into the fold. Basically her main goal is finding the missing shards of the weapon her patron is bound to and serve the faction she's apart of allowing the DM to tie the earlier parts of her life in as storyhooks for the party as needed. Does this sound reasonable? Or does it fall into the same category of eyeroll and groans like most amnesia stories?
Not remembering what happened prior to 13-16 isn't that big of a deal I would think as most adults don't remember much prior to that age range normally. However I'd presume the "amnesia" occurred during the time the character discovered the shard or soon after which would lead me to believe (if I was in the characters shoes) that the shard may of in some way be connected to my amnesia, making the journey to recover more shards not just be about completing the weapon the patron is attached to but potentially unlocking lost memories and/or possibly discovering the reason behind my amnesia.
So I don't think that the amnesia will be much of an issue but I do see one potential issue. And that is that your character essentially is on the path of a "chosen one" style character. Meaning that the various adventures your party goes on in some way could be connected with your character's development, with your DM not only making your past part of story hooks but also the completion of your patron's weapon apart of the journey. Potentially rubbing other players the wrong way, since things could primarily be about your character and not their own. Therefore I'd hope your DM have the foresight to explain all this to the group before proceeding and make sure they are on board with such. And to help in that regard, two good examples of this working is Avatar: The Last Airbender if your DM chooses to make you a central focal point or how Keyleth was treated with her Aramenté on Critical Role if your DM chooses to make your characters personal quest more a side quest for the group that is done at their leisure. Also, I'd look to the character of Kagome from Inuyasha as she very much has the "chosen one" thing going on and is looking to collect shards to complete an artifact very much like your character. Which makes using her as an example actually quite perfect, assuming some bit of her wasn't already a source of inspiration for your character considering the strong similarities between the two.
Finally on the above point of Kagome's mission to collect the shards of the Shikon Jewel, if I was your DM I'd definitely consider that others would be seeking (or finding) the shards of your patron's weapon. Leading to all sorts of issues as seen with those who sought or accidentally came across the shards of the Shikon Jewel. Plus there is to consider just how your patron's weapon comes together, does it come together automatically? Is a special ritual required? Does it need to be smithed in a special place? And then what happens when it's complete? Does handling your patron become like any other sentient weapon or something more? Do they ask you to perform a special ritual to free them from the weapon and if you comply then what? Do they turn against you and your party resulting in an epic boss battle? Seeking your magic power and life out of necessity (to finalize their resurrection) or simply out of greed for more power. Leading to your character potentially having to sacrifice their power (if not their life) to end your patron. Or are they grateful and bestow upon you a boon of some sort?
And since these came to mind while finishing up, here are some other sources of inspiration: