Gunblade is such a frustrating item

Some champions want it because it's the only source of Vamp for magic damage dealers.

Some champions want it because the active is EXACTLY WHAT EVERY AP ASSASSIN NEEDS TO FUNCTION - same reason Botrk is popular when it's strong, the active is literally the only reasonable way for some champions to get a reliable ranged slow except gunblade also has respectable base damage and ratios.

Some champions want it because they can use all the stats efficiently, but they usually want it the least because if you have the scalings to efficiently use all the stats then you have he scalings to buy better items. These are the "intended users".

Some ap champions want it not for the ranged slow, but exactly for the additional ratio - same concept as Deathfire Torch, it's like a Lich Bane with pure combat stats and the base damage to be useful before 300 AP.

Seriously, the item is such a hodgepodge of things that people desperately wish were on items that fit them better. Nobody actually wants to buy Gunblade because it's wholistically good on them, and it's been tuned as a way to keep things at a certain price point - "Sure, the ability to omnivamp/targeted ranged slow/nuke just that bit more/buy AP and ad at the same time is abusable on X champ, but they have to spend 3800 on mostly shit they don't want to do it, so it's heavily gated"

Imagine if you had a Haunting Guise + Revolver upgrade with Gunblade active -broken as hell, right?

Imagine if you had a Needlessly Large Rod/Bf Sword upgrade with Gunblade stats that was remotely price effective - Jax and Ezreal would have a field day.

Imagine if AP champs had a Death's Dance equivalent - actually, you don't need to imagine. Riot tried for years to balance spellvamp with Morde and Vlad and eventually just gave up, basically throwing up their hands and saying "Fine, you can't get spellvamp without a lot of ad, no CDR, and 3800 gold. Sorry everyone else, that's apparently what it takes"

Gunblade is such a tempting item, but it's designed to just not really work on anyone that actually wants it, because it's broken and toxic for all the same reasons it's desirable. It's a lot like frozen mallet, old thornmail, and atma's in those respects but people that wanted those items have other options that full fill the same niche in a non-toxic way. Gunblade has no such replacements.

I don't really know where I'm going with this, but I've been thinking about it a lot. I don't really have a good solution, but I do think the way things are kinda sucks.