So I actually studied Pewdiepie's build in Dark Souls....it sucks. What else can I say?
This is what he used to kill Gwyn.
Left hand, Greatshield of Artorias.
Right hand, Pyromancy Flame.......not Ascended by the way.....He had Fire Orb. Dunno his other spell.
He had the Gargoyle Halberd...I believe fully upgraded.
He also had the Dragon Head. For some reason.