The seven stars symbolize the complete church. The church is safe in the right hand of the Son of Man, which means it is under his care, acceptance, and blessing.
The sharp sword coming from his mouth represents his powerful message and judgment (see Revelation 19:15; Genesis 3:24; Ephesians 6:17; Hebrews 4:12). Jesus announces both grace and judgment, but here the focus is on his role in carrying out judgment (see Revelation 2:12, 16; 19:15, 21; compare Isaiah 11:4).