There are a number of ways to deal with this, many of which depend upon your skill and the materials used.
1. Sew a tiny rolled hem. If you press the hem first, you can indeed sew a hem using as little as 3/8 of an inch. This requires more patience than skill as it's 90% ironing.
2. Sew a facing (or actually fully line it). Essentially cut the whole skirt again in similar colored fabric, sew right sides together along the hem, clip the curves and points and turn right side out. this requires a waistband of some sort usually to enclose the skirt and lining fabric at the top. More careful sewing skill and fabric required, but my favorite for best finished appearance.
These two options are best for woven (non-stretchy) fabrics.
3. Fray Check, which is indeed glue. TEST FIRST as it can discolor some fabrics. It's runny so if you put too much down it makes the fabric hard and crunchy. I only use Fray Check on ribbon or cord where sewing some sort of hem isn't an option.
It is a better use of your time and money learning to sew. It is a skill that reaches far beyond cosplay.