It’s fantasy, yes, but fantasy that sticks to a specific historical period more closely than is usual for the genre. That historical period has been roughly noted as being around 900-1200. That’s not a strict limit though, with there being outliers in what kind of weapons are available, but plate I recall being mentioned as specifically being outside of the period-theme that they’re going for.
As for armour, there’s lots of kind that I would like to see. Something like brigandine could still just about fit the time-period, if you go for the earliest models. It also combines nicely with other armours, so you could make layered versions.
