I read later that Goju Ryu, being Okinawan (with direct cultural links to China), did not originally have grades (traditional Chinese gongfu - such as our family style - does not possess formal grades). Gradng was only forced onto the style by the Japanese government (I believe initially in 1936 [as part of the cultural splitting with China - in preparation for war] - but this was not taken-up with any great enthusiasm at the time in Okinawa). Grades were finally adopted in the 1960s - as Karate-Do spread all over the world and became popular.
I note that the rank of "5 Dan" carries the honorific of "錬士" Jap: "Ren Shi") [or Chin: "lian4 shi4"].
錬 (Ren) = forge, cultivate, temper
士 (Shi) = warrior, scholar, skilled
Therefore, "錬士" seems to mean "Refined Warrior-Scholar".
錬 (Ren) = left-particle - 金 (jin1) - "Metal"
錬 (Ren) = right-particle - 柬 (Jian3) - "Refine"
金 (jin1) [left-particle] = 亼 (ji2) [upper element] - mark, collect, gather (as in to "find" iron ore)
丷 (ba1) [middle element] - (contraction of "八") - in old dictionaries "two blocks of metal" - as in "two separate the iron ore" through the smelting process
士 (shi4) [lower element] - in old dictionaries, an "upside down rritual axe" made of metal (the product of smelting and forging iron ore)
柬 (Jian3) [right-particle] = 束 (shu4) [outer element] - select, gather, bind (tie) +
八 (ba1) [inner element] - "8" or in this context - to "divide" and "separate"
It is interesting to see "士" (shi4) meaning "scholar", "warrior" (traditional) and "metal axe" (ancient).