Garrick runs into a librarian, a bard who has seen better days, and might just have a story to add to his collection, if he can survive...
The quest starts with a chance encounter north of the carnival at Nashkel. A distracted librarian, retiring to a better climate, happens on the party.
If Garrick and the party are reasonably nice to him, the gentleman gives the party a book that Garrick has always wanted. With a close reading, the party can discover a bard who has wandered his last days as a mortal, but has stuck around for more fun.
If the party heads to the west central part of the Ulcaster Ruins area, they can find the ghost and his companions. A fierce battle, loot and a good story await the successful adventurer.
You can upgrade one of the treasures by taking it to Sorcerous Sundries.
If you have difficulty with Myr'Cutio, remember he is a bardic ghost and still has spells and the abilities of a blade. As a ghost, he cannot be hit by nonmagical melee weapons. He will also seek out Garrick specifically and any other bards in the party. Therefore, the party should prepare accordingly, using any protective potions or spells in their arsenal, as well as ranged/magical weapons and offensive spells.
If you *still* have difficulty, sometimes, discretion is the better part of valor. Garrick and company may want to beat a very brave retreat, and live to fight another day when they have more experience under their belts. The prize will make it all worthwhile, but it shouldn't be up for grabs to rank amateurs ;).