What does Malachi 2:2 mean?
The priests of Israel have been dishonoring God by offering impure sacrifices (Malachi 1:8) and by worshipping with bitter and lazy attitudes (Malachi 1:13). Just as these men should have known the proper forms of sacrifice (Leviticus 22:17–30), they also should have known the consequences of disobedience. The Law spelled out the suffering that would result when the people disobeyed (Deuteronomy 28:15–68). Here, God reiterates these threats to bring curses on those who dishonor Him.The fact that Israel has been disobeying God means that these consequences have already been in effect. God's people should have recognized their own sin and seen their struggles as the results of their own choices. Sadly, instead, they blame God for their hardships and question His love for them (Malachi 1:2)!
The "blessings" being mentioned here probably include two aspects. The first is the spiritual ability of the priests to intercede for the people. While the Bible says that the prayers of righteous people are powerful (James 5:16), it stands to reason that the prayers of the unrighteous are ineffective (Jeremiah 14:10–12). In this case, God is actually threatening to turn the priests' attempts at blessing into curses. The other meaning of the "blessings" at risk is likely the income given to the spiritual leaders.