Confused about the word "which"

I need help understanding the following statement and how the word "which" relates to everything before it.

"Every judge of a superior court shall, before entering upon the duties of his office, take and subscribe an oath that he will support the Constitution of the state of Washington, and will faithfully and impartially discharge the duties of judge to the best of his ability, which oath shall be filed in the office of the secreatary of state."

My confusion stems from the fact that the way the word "which" is used, it is difficult for me to determine when the oath is required to be filed. Let me reword it in a way that may simplify the question:

"Every judge of a superior court shall, before entering upon the duties of his office, take and subscribe an oath....which oath shall be filed in the office of the secretary of state."

Is this correctly construed to mean, "Which oath shall be filed in the office of the secretary of state, before entering upon the duties of his office?"

Thank-you, Toni