Dark Souls 3 will be receiving patch 1.04 which will offer a variety of changes and improvements along with changing the way certain weapons work.
The patch notes indicate a “performance adjustment” for Greatswords along with a battle performance adjustment for Dancer’s Enchanted Sword and Winged Knight Twinaxes, performance adjustments for the Soul’s Greatsword and Farron Flashsword. No specific changes were outlined so it’s hard to say whether the weapons were “nerfed”.
The patch will also fix an issue where multiple items become unusable at Road of Sacrifices, Farron Keep and Cathedral of the Deep after you’ve finished the game once. Then there are the general adjustments to balance and bug fixes.
The patch deploy on April 18th for PS4 at 7 PM PST/10 PM EST and for Xbox One at 5 to 8 PM PST/8 to 11 PM EST. The PC version has the patch listed as 1.03.1 and releases at 2 AM PST/5 AM EST on April 18th (it should be available now in fact).