I have usually seen the gold over pitch approach. The pitch is roughly molded in the general shape and then thin gold plate/sheet is placed over the shape and then stamped and chased onto the gold. The pitch(ish) material takes and then holds the new indentations in place. Thus the form takes shape (every pun intended
) and you have a hardened gold covered hilt.
There are some details I'm leaving out, but this is the simplified explanation.