[quote=@Hantu Kongkek]
Well; his size means he's likely neither assassin nor caster, Jackson's already the Archer so he can't be that, a Saber would expected to be carrying a way fancier sword, and he's not a girl which most Sabers seem to be. He's wearing armor Jackson would likely recognize as something more attuned to old-fashioned cavalry as opposed to direct melee, ruling out berserker.

Plus a class isn't as secret as the name; the class would be obvious the moment they do battle.
[/quote]

Galantine and the swords of half the Grand Order Sabers have some words to say. Arthur and Mordred were only secretly girls, and besides them it's really just Nero/Attila. I don't get the logic behind "he's a guy and his sword isn't glowing like all unactivated Noble Phantasms do, he can't be Saber". 

[quote=@ADamnFiddle]
<Snipped quote by Scrapula>

I mean again, personally I don't really care. I just feel that to be able to discern those sorts of traits from simple glance seems a bit odd is all~. Tbh the end result should not matter all the same. 
[/quote]

This is pretty much it, honestly. The issue is that I don't plan on setting a precedent of people doing asspulls at the drop of a hat which is largely fueled by OOC knowledge. What you know OOC shouldn't mean that your character figures things out super-easily because you know them. If I allowed that, then it's a slippery slope that I have no intention of walking down.

It's not a balancing thing, since it's hardly like knowing he's Rider helps you, but the issue is moreso that this post wouldn't have been made if I had made Servant CSs secret. 

If you legitimately want to argue contrary to that, and say that without knowing anything about him save his appearance, you would have made that post exactly the same, then I really don't know what to say.