鍵{かぎ} seems to have explained in the other answer. 鑰{やく} is difficult to read. I have never seen this one as stand-lonea standalone character. So, I searched to a little bit.
- I found a book called 秘蔵{ひぞう}宝鑰{ほうやく} written by 空海{くうかい}, a Buddhist monk, 1200 years ago.
So, a person who follows his Buddhism teaching/school may be familiar with the word. 宝鑰 seems to have the meaning of ";The;the key to treasures" : 宝(宝の鍵。宝物庫を開く鍵。according。) according to goo辞書. (宝 is ";Treasure;treasure";"; in Japanese.)
- I also found 印鑰{いんにゃく}神社{じんじゃ} which is a Shinto shrine : 神社(神社{じんじゃ}).
According to wikipediaWikipedia, it seemsshrines with this name seem to still exist mostly in Kyushuthe Kyūshū region, but some in Tohokuthe Tōhoku region. Anyway, this shows that it is not only limited to Buddhism.
The meaning of 印鑰{いんやく} by itself is, according to goo辞書:(印 is a seal which confirms something),
官府の長官の印と諸司・城門・蔵などの鍵。: "The seal of secretary of government and "key" to the gate and warehouse, etc.
The seal of secretary of government and "key" to the gate and warehouse, etc.
(印 is a seal which confirms or certifies something.) So, I also think it was used a long time ago in the legal system.
苗字{みょうじ}ネット has the family name 鑰山{かぎやま}. But only 20 people have the name. 三鑰{みかぎ}さん 50 people, 鑰山{かぎやま}さん 10 people. So, the name has 鑰 is very rare, but still exists.
- 苗字{みょうじ}ネット lists the family name 鑰山{かぎやま}, but only 20 people have the name. (Similarly, 三鑰{みかぎ}さん 50 people, 鑰山{かぎやま}さん 10 people.) So, family names using 鑰 are very rare, but do still exist.
