The word which he sent (ton logon hon apesteilen). Many ancient MSS. (so Westcott and Hort) read merely ton logon apesteilen (he sent the word). This reading avoids the anacoluthon and inverse attraction of logon to the case of the relative hon (which).
Preaching good tidings of peace through Jesus Christ (euaggelizomenos eirēnēn dia Iēsou Christou). Gospelizing peace through Jesus Christ. There is no other way to have real peace between individuals and God, between races and nations, than by Jesus Christ. Almost this very language occurs in Eph 2:17 where Paul states that Jesus on the cross “preached (gospelized) peace to you who are afar off and peace to you who are near.” Peter here sees what Paul will see later with great clearness.
He is Lord of all (houtos estin pantōn kurios). A triumphant parenthesis that Peter throws in as the reason for his new truth. Jesus Christ is Lord of all, both Jews and Gentiles.