To get Fadeshear in Act 2, you can loot Lyrium Smuggler's Corpse in the cave during Act 2 quest "A Bitter Pill" (Sundermount Mountains) or steal it from Wade once he moves his shop to the Hightown Marketplace.
Fadeshear Sword (Act 1):
1) Go to the Docks District in Hightown at night.
2) Speak to Wade and convince him to sell his swords to the Starkhaven mercenaries.
3) After the dialogue, kill the mercenaries.
4) You will find the sword in one of the chests.
Fadeshear Sword (Act 2):
1) Loot the Lyrium Smuggler's corpse during "A Bitter Pill".
2) Steal the sword from Wade's shop in the Hightown Marketplace.
In all cases, acquiring the sword will require high cunning or high dexterity or both.