Baldur's Gate 3 has an incredibly easy-to-miss unique weapon, which can only be unlocked by enabling a very specific trader in Act 3.
As the Reddit post below explains, the greataxe is actually pretty easy to get hold of - as long as you know where to look - but most Baldur's Gate 3 players will have tragically missed out on the weapon. Why? Because enabling its trader to sell you the item in Act 3 is an utter pain in the ass, and can only be achieved by following a set of very specific steps.
That weapon is Sethan, a Very Rare Greataxe. While it might not come with best-in-class damage, necessarily, what sets it apart is its spell, Spiritual Greataxe. Casting that allows you to summon a 'twin' of the weapon, which is capable of flying around independently of the caster, and dealing a very impressive 3d8+2 Force damage. That's a max of 26 in a single hit, and bear in mind that's in addition to anything you pull off with the corporeal form of the weapon, too.
This is the most missable unique weapon in the whole game from r/BaldursGate3
As for getting your hand on it, however, for starters you'll need to track down a character named Ferg Drogher in Rivington. Drogher is on the lookout for Shadowheart, but if you've redeemed her through Act 2, he'll immediately recognise her as a Selunite, pointing her towards her punishment at Baldur's Gate's Sharran temple, the House of Grief, before quickly ducking away. He'll never show up as a trader again, so to avoid losing out on his wares forever, you'll need to leave Shadowheart in camp unless she's fulfilled her Dark Justiciar goals.
Next, begin questioning Drogher about how he acquired his unique wares. Eventually, you'll be prompted to roll an 18 Persuasion check, just to have him show you his better gear. It's unclear if he vanishes forever if you fail the Persuasion check, so proceed with caution.
After this, you can buy Sethan from Drogher! However, if you look at his wares before succeeding the Persuasion check, it turns out you'll never be able to buy Sethan from him even if you succeed the check later on - this is apparently a bug, although it's not one we've ever heard developer Larian comment on before.
But it's not just Sethan that Drogher has in his arsenal. It turns out he has a special cape that'll let you cast the 'Dominate Person' spell for free, and there's also another clothing item for characters that increase their Concentration capabilities when casting spells. Hell, Drogher might be one of the best merchants in all of Baldur's Gate 3.
Check out our guide compiling everything we know about Baldur's Gate 3 DLC to date.