I just just want to offer some tips for new players want to play tank:
1. Please consider use Heavy Swing and Retaliation and stay away from Weapon Throw.
Reprisal and Rampart are not recommended because these 2 skills are only ideal in smaller scale PvP such as the Feast, but not Frontline.
Weapon throw in general not ideal because it can be easily counter by enemy healer's rescue and most of jobs have escapers.
The next point will further reinforce on why Weapon Throw is highly not recommanded.
2. Choose a visible symbol such as Circle and only apply on the target you about to stun.
The basic rotation is charge > stun > Heavy Swing back to your team.
When target got knock back towards your own group, this target will less likely to escape with escaper and you also cut him off from enemy healer's rescue. This will slow down a lot of veteran melees.
3. The recommend target priority in first 5 mins is Range > Melee > Tank > Healer in larger scale PvP.
After 5 mins, the target priority changed to non/low BH Tank > non/low BH meele > Range (any) > Healer.
The priority changes according to BH, any low/non BH tank/melees usually reflects to their skill (not 100%, but on average) and they are easier to kill.
Focus healer only recommend in smaller encounter but in larger scale pvp you want enemy healer to choose a target to heal instead of just keep healing himself.
If there is no range and you must choose a melee, priority is Monk > Reaper > Samurai > Dragoon.
The reason is obvious, Monk has no range and must be in close quarter for Dragon Kick and Reaper porting mechanic is clunky and most people can yet master timing of shield.
Samurai and Dragoon have much better escaper; therefore not on high priority.
4. Most important of all, although you are referring as a tank but smart DPS will always ignore you and go for Ranges.
You are not a DPS nor Tank, you are just a support role to setup the kill for your team.
Those fancy plays you saw in 1 v 1 or Secure are nothing but Veterans using their knowledge as weapon on players that don't know or not trying to learn.