An "eyewitness" is a person who saw something happen, and a servant of the word is a person who serves God by telling people God's message. You may need to make it clear how they were servants of the word. Alternate translation: "saw what had happened and served God by telling people his message" (See: [[rc://en/ta/man/translate/figs-explicit]])
The word "word" is a synecdoche for a message made up of many words. Alternate translation: "servants of the message" or "servants of God's message" (See: [[rc://en/ta/man/translate/figs-synecdoche]])