In the Bible verse Mark 16: 15-20 would you say that the Lord gives us authority to bless?

The signs in 16:17,18 were promised to the apostolic community (Matt. 10:1; 2 Cor. 12:12), not all believers in all ages (cf. 1 Cor 12:29,30). All (with the exception of drinking poison) were experienced by some in the apostolic church and reported in Scripture (e.g., Acts 28:5), but not afterward (cf. v.20). I don't think the words I bless you in the name of Jesus would also be appropriate.