Words are spoken of as if they were metals that need someone to clean the bad parts out of them. Alternate translation: "is like a precious metal from which someone has removed all the useless material" (See: [[rc://en/ta/man/translate/figs-metaphor]] and [[rc://en/ta/man/translate/figs-explicit]])
The word "shield" is a metaphor for something that protects a person. Alternate translation: "he protects those who come and ask him to protect them" (See: [[rc://en/ta/man/translate/figs-metaphor]])