plaque belts -
Lorifactor - wide variety of types and styles, high end finishing
Bractea - small variety, also very nice finishing
Klinstejn - not as high end as the first two, but serviceable and much less expensive
rowel spurs -
Armour and Castings can be gold plated as well
Sword suspension... well, by 1415 on new armors we start to see a discrete, thin sword belt being worn. But earlier in the 15th century (so still appropriate for Agincourt) we see on effigies swords magically suspended directly from the plaque belt, which is how I wear mine. To accomplish this we use a small staple attached to the back of a molded throat locket through which a leather strap passes and buckles around the plaque belt. There are historical survivals of throat lockets with such a staple, and there are also artistic depictions of scabbard throat lockets with a buckle riveted directly to it for a leather strap.
Just a word of caution though, worrying about spurs, plaque belts and sword suspension is really the absolute last thing you need to worry about putting together a high end 1415 kit. Those are finishing touches, and especially in the case of the plaque belt, it needs to be measured to fit around your finished cuirass and fauld. If you go with a custom armorer that does good historical work, this is a long ways down the road. I think in another thread somewhere you mentioned contacting Anshelm Arms.... I would head over to the
Armour Archive and search for some reviews, they can sometimes be difficult to deal with and not always deliver on their promises.