In those worship services/concerts I have attended, raising ones hands is a sign of praise and adoration.
I once attended a Mormon service, and the speaker was explaining why Mormons raise their hands when they sustain their leaders. He quoted a passage from the Pentatuch, I don’t remember the passage, in which Moses had his hands raised during a battle…and as long as he kept his hands raised the Israelites had the advantage, but when he became tired and his hands fell, they began to loose. So those who “sustained” him kept his arms raised until the batlle was over and Israel was victorious. That, he said, is the beginning of why God’s people raise their hands…and why LDS raise their hands to sustain their leaders…I thought it was a very clever sermon which drew from the scriptures the imagry of sustaining a prophet.
In those more emotional Prostestant services I have attended…including some concerts…there is a verse often quoted about “raising holy hands unto the Lord…”
Love is Patient