Depends on the medication. They won't give you extra confidence (at least that I've noticed), but hopefully will dial down the feelings of anxiety.
Diazepam, I think, is a muscle relaxant, and it can make you a bit drowsy and slow, so a bit drunk in that sense. I used to be on quite a high dose of a similar drug to this, and it doped me up quite a bit, but also did give me a bit of a feeling of "eh, who cares" about things I had panicked about previously.
Beta-blockers like Propranolol really just treat the physical symptoms of anxiety, so they slow down your heart rate, lower blood pressure etc.
I'm taking Promazine for anxiety at the moment, which isn't very common, as far as I know. In tiny doses it just chills me out. Stops the loud anxiety thoughts, makes me physically relaxed, easily drowsy. No confidence boost, sadly.
I guess meds are best to help with the anxiety reaction, the panic, all the physical symptoms of it, while some CBT or other therapies is where you're more likely to find help for confidence.