I found Deithwen to be much better than that Zerrikanterment, you find while following Iorveth and you have to go through the caves, instead of following him blindly and into the caves to fight the Arachas; right before going in, take a left. You will come to a dead end and between 2 Arachas, one has a unique shell on its back. Kill them and loot the skeletons to the far right.
Deithwen with 3 Ysgith is better than Zerrikantement with its 2 slots having 2 Ysgith, as it does more damage 53-59 as to 51-56; and because majority of the enemies in chapter 3 are large monsters and gargoyles, it does to those kinds 25% extra damage.
Agreed. Btw what is this sword from Gargoyle side quest that everyone's been talking about?