Medieval glues were water soluble, which meant they became tacky and lost cohesiveness in damp conditions. Obviously not wanting their fletchings to fall off this meant they would not only glue the fletch onto the arrow shaft but also tie them on too. Today's modern glues have no such issues so you can have your arrow with just a bit of binding at the start of the feather and leave the rest bare. This little bit of binding is just in case the front bit of a fletch lifts during use. The binding then prevents a nasty accident if you're shooting bare handed as an unbound fletch can dig into your hand when shot (I've seen this happen).
If you want a fully bound fletch then no problem. This will make your arrow look the most medieval too. I'd normally bind an arrow with black thread so that it's visible against the wood arrow shaft, although a brown thread is more period as they would not necessarily waste dye on a thread that isn't there to look good. However I can bind the fletch with any coloured thread you so require. So pick one of the following...
Write down if you want part or full binding. e.g. full binding
Write down the colour of the thread you require. e.g. black