The Infernal Rapier, did you miss it?

A lot of people do, because they don't bring Wyll to the Act II Finale. Typically because your party will be your 4 most powerful characters, and canon Wyll won't be one of them... unless you have re-specced him into something useful for the big end fight (Not a Warlock).

Will you miss having the Infernal Rapier?

My opinion is "No". Most of the powerful "Martial" Warlock Gear is not available until Act III. And in Act III, you can also get the Legendary Rapier "Duellists Prerogative" pretty quick.

SPOILER ALERT* (Speak to Lora, in the Fist Barracks Office, as soon as you enter Baldurs Gate Lower City, at the the Basilisk Gate - you will get the Quest "Save Vanra". Make sure you Save Vanra... Vanra is Ethel The Hag's new victim).

Assuming you are playing Wyll in character as "Blade of the Frontiers", clearly you should be playing him as a "Pact of the Blade" Warlock. Bind the Duellists Prerogative as your Pact Weapon, its a +3 Rapier that will reward you with an Extra Attack, an Extra Reaction and Extra Damage if you spend that extra Reaction.... per turn!!

When you have the Prerogative, the Infernal Rapier will just be a brief memory gathering dust in Karlach's backpack... you'll never use it again. If anything, it may get re-purposed as a "Stat Stick" for a surplus Camp Wizard or Sorcerer... but even they will have better options quite quickly in Act III.

Then of course there is the Harmonic Dueller (+1 Rapier, Act III)... Bind the Weapon, then add your Charisma Modifier to Damage... again!!

So, you get the Infernal Rapier right at the bitter end of Act II. Within an hour of starting Act III, it is redundant.

So don't sweat it, don't start re-loading old save files and playing Act II twice....you missed nothing.