Is it permitted for a woman to stand in an assembly and talk even if it is for a testimony?
In my opinion, yes it is acceptable for a female Christian to speak in a church assembly, and to give a testimony. The matter of interpreting 1 Timothy 2:11-15 and 1 Corinthians 14:33-36 is a difficult one. I believe that the thrust of these passages is that women in the church should be in a submissive role. This does not mean that they literally cannot speak at church. We know from various passages that women did indeed speak at church. What it does mean is that women should not "speak" in an authoritative way. Preaching by women in front of the whole church seems ruled out by these passages. Sharing a testimony is not a matter of authority, so if it is done with a submissive spirit, I cannot see why it is not biblical for a woman to share a testimony in church.
Please note that this is a very simplistic treatment of these passages. Commentators have a lot to say and there are many opinions. I have given you mine and perhaps you should look elsewhere, read a commentary, think for yourself and so forth until you are satisfied what God, through Paul, is saying in these passages.
John Oakes, PhD