The weapon has been assembled, but it lacks the power that made it a legend. In order to restore it, you must receive three blessings: one of fire, one of frost, and one of beasts.
The first blessing mentioned in the journal is that of fire. The journal reads:
"He describes an ancient monolith, perched upon the edge of a precipice extending from the cliff where the searing magma falls into the sea. I believe the location he speaks of is just overlooking Tor'goroth's Tooth."