I’d go for the first build @Vanic suggested. However, if OP doesn’t find the aforementioned builds suited to his taste, he can always go for … -> Hoplite c1 -> Cataphract c1 -> Whatever C7 he finds attractive.
This way, you can use both Finestra and High Guard for even higher block rate, benefit from mounting companions, have slightly better mobility, and all the while contributing slightly more dps.
As for C7, you can do the following (suggested):
Templar: If you’re keen on doing guild stuffs or make your own guild.
Rodelero: Great CCs (No targe smash, however) for PvP, especially for just one circle
Hoplite C2: 100% uptime on Finestra and higher base dmg for other dps moves
Dragoon: Tons of damage
Or other choices for C7, too, that aren’t too detrimental to your build:
Cataphract C2: more AoE dmg and mobility. Still, Hoplite C2 would still be a better choice.
Swordsmen C2: kind of pointless compared to all the other better choices, but it’s available.
Squire: Arrest can’t be used while mounted, so it’s more like a remote self-repair class.
Avoid the following classes because of cataphract:
Fencer, Dopplesoldner, Shinobi, and Barbarian.