The DM believes that bladepact warlocks are weaker than other warlock builds. So to even the odds so to speak, each Otherworldly Patron will bestow upon the bladepact warlock the ability to conjure up a copy of a specific magic weapon. One that will use a non-standard damage die equivalent to the bladepact warlocks Charisma score to a maximum of 1d20, or two damage dice that roughly approximate it up to 2d10. The weapon will also deal at least one kind of energy damage in addition to force damage as well as slashing or piercing damage. The DM will build and present the weapon with the players input. If the PCs Charisma score was 16 when they acquire the Pact of the Blade, their pact blade will do 1d16 or 2d8 acid, force, and slashing damage for instance. The original pact blade is kept by the warlock's patron and has an actual enhancement bonus, plus each time one of the copies is conjured it counts as having been made on whatever plane the warlock is currently on. If the original weapon were to be stolen or destroyed it would significantly weaken the Otherworldly Patron's standing and the patrons other warlocks.