Evolution

It was superior to other golems in a qualitative sense. It wasn't just bigger and meaner than other golems, it possessed much greater power for much fewer flaws and limitations.

Furthermore, based on the insights that Rui had logically deduced and inferred, he had gotten a much greater understanding of how it had come to be than when he first saw it.

'Smelting.' Rui mused. 'Based on the inferred model of its geobiology, it most likely smelts a Senior-level esoteric substance from rocks and ores that it heats and melts in its crucible, before integrating that substance into its body.'

That would explain how the golem came to possess a body made up of this substance. The process of smelting was something used by blacksmiths and mass production factories to extract desires substances from a mixture or an ore, relying on the differences in density of the melted ore and the desired substance.