So this guy is clearly Carnor Jax, whose ambitions and exploits post-Episode VI are laid out in Crimson Empire (1997). Here he is with Kir Kanos- I believe the young people call it tea-bagging.
Rumour has it that FFG was prevented by Lucasfilm/ Disney from calling him Carnor Jax, so they settled for the bland 'Royal Guard Champion' instead.
I used a red undercoat with a sepia wash, then dark grey with a black wash for the armour and dark blue/ grey with a black wash for the cloak. Whilst the iconic art above has the double vibroblade with a black haft, I went for gold as seen in other images.