Angels are masculine because they are superior beings while human beings are feminine because they are regarded as the weaker sex. But in reality angels are male and female because Jesus said in the beginning God created them male and female.
Matthew 19:4 ESV He answered, "Have you not read that he who created them from the beginning made them male and female,
Isaiah 42:19 KJV Who is blind, but my servant? or deaf, as my messenger that I sent? who is blind as he that is perfect, and blind as the LORD'S servant?
Isaiah 42:20 KJV Seeing many things, but thou observest not; opening the ears, but he heareth not.
Isaiah 42:21 KJV The LORD is well pleased for his righteousness' sake; he will magnify the law, and make it honourable.
1 Corinthians 13:9 ESV For we know in part and we prophesy in part,
1 Corinthians 13:10 ESV (10) but when the perfect comes, the partial will pass away.
God is heart only.