To maximize your stamina damage output out all your points in stamina.
Wear gear that boosts your weapon damage and max stamina.
Wear stamina enchants on all gear and weapon damage glyphs on all jewelry.

Stamina classes have great burst in PvP and some even have good survivability. Today's meta dictates magicka play, but that does not mean you can't play as stamina.

You'll have enough magicka to use mist form without putting any attribute points into magicka. I'm not sure what other vampire skill you'd be using in PvP besides the ultimate. I would put all or at least almost all of your attribute points into stamina, that's going to be the way to go to improve your damage and survivability (i.e. more stamina to be able to block and dodge roll).

There are plenty of stamina based characters in Cyrodiil, so don't be disheartened if you've noticed mostly magicka. I regularly see stamina skills like dizzying swing, poison injection, etc. in my death recap.

You mentioned you have dual wield, what is your other bar? What class as well?

There really isn't a "magika meta" and everyone is magika, at least in pc NA (can't speak for others). You need to remember that tons of people played magdk when the game was released and now that magdk was patched, people are trying it out. Stam, was stupidly overpowered and being closer to balance means people can't one shot everything and now are exploring other options. The "meta" is whatever class you play, you should have one sustain set and one dmg and probably a monster helm or heavy armor. You also have to remember is that there are players that will go for whatever is the easiest and cheesiest class and copy a build. Several patches ago the game had tons of mag sorcs. Shields were cut to 6 secs from 20 and people quickly dropped class (those that didn't want to adapt or mastered the class). Just remember, people are VERY reactive in this game and if they can't 1vx everything, they got salty.

In short, play what you like and get good at it. There will always be patches and changes and some classes fulfill roles better than others. So that is a question you can ask yourself. Do you prefer solo, small group, 12 person team, or zerging? My solo sorc is very different from my small group and my 12 person will change to support. My stam dk, is meant to focus heavy armor healers which are all vampires. So cut armor and redmountain with dawnbreaker.

Which is stronger? It depends on what class you are playing. Stam vs mag blade, i'd personally go for stam. A magblade is a pretty rare sight, but again, the people who are staying with it are very solid. If Heavy armor is nerfed a little bit, I think the class would be in a good place. As templar, i'd go magplar over stamplar. Right now heavy armor magplar are very strong. Sorc, both are strong! Stam hits hard, has awesome movement, insane heals and third bar. Mag sorc is very good too and can fit many roles. However, requires a LOT of practice to stay alive and if you are focuses your shields wont last. Mag sorcs can be one of the easiest to kill, unless they are good. Mag dk vs stam dk are very different. magdk is about resources and dots and great in groups. stam dk can tank and dps. I kill stuff all the time with my stam dk but don't like the cheesy rotation of dizzy swing.

So, tons of sets, a lot of variety, more balanced, so play what you want and get good. If stamblade, probably can't one shot a tank and heavy armor (the injustice) but you can stay to the side, wait for a healers heath to go down, and burst them to zero, which, will probably wipe the other group.

Keep things simple in cyrodill. Put a two hander on back bar with rally and vigor and whatever buffs your class skills has and maybe shuffle. Use your DW bar as you see fit and you will learn how your play style will work out for you. But that is my advice, back bar two hand with rally. Go from there.