I too would be careful with the ribbon. Dharma Trading sells a silk bias 'tape', it dyes up and makes into beautiful embroidery ribbon. But your point. For a church costume, I would zig-zag the edge, turn 2X and stitch down. You could also blanket stitch it. If you can find twill tape you could try it. I would think it would work. You could also use a contrasting color, if you had a beige costume, you could add a rust colored sash, and then use the fabric from the tie to be the bias for the neck and arms.