No matter how perfectly you wrap a quill body on a fly, without reinforcement, it will be far from durable. A sharp trout tooth can sever the quill, causing it to unwravel in a mess and render the fly unusable.
One solution is to coat the shank with super glue prior to wrapping the quill. Pressure from the quill contacting the adhesive will cause it to set. In this case, even if the quill gets cut, it’s far less likely to unravel.
Applying a light coat of thin, UV cure resin over top of the quill then giving it a healthy shot of UV light is probably the best way to go. It adds a bit of weight but you get shine and the quill can’t be cut or come unraveled.
An old school reinforcement method involves leaving a tag end of white thread hanging off the back of the body prior to wrapping the quill. Once the quill is wrapped and locked down, the tag end can be counter wrapped around the body to keep it from unraveling. A light skim of thin head cement is then applied. When the head cement dries and contracts, it leaves a very durable body and those white thread counter wraps all but disappear.