For soloing, Paladins can joust, using root to keep a mob in place while moving in and out of melee range to take swings at it with a high dmg/high delay weapon. You can also sit in between swings to med up. However root can be really unreliable, sometimes breaking as soon as it's cast. Later in levels you can use the
Deepwater Helm to heal to full.
Shadow Knights can fear kite, using dots and a pet to speed up the process to an extent.
Polished Obsidian Great Axe is really decent for soloing as it procs at level 40, 9 levels before SKs even get Invoke Fear which costs quite a bit of mana. Procs aren't always the most reliable, even with high dexterity, but you can always use your short duration level 15 fear as needed to buy you time.
In groups, both classes can act as pullers with Shadow Knights using darkness with feign death and Paladins using lull with root. Most groups will likely only ask you to be on tanking duty since this server is overrun with monks. On raids it's usually just about offtanking and protecting the Enchanter. Think of yourself as a linebacker that can't tackle for shit but is really good at getting in the way. Paladin heals go a long way on raids where the mobs have aoe spells and damage shields, whereas Shadow Knights can only really help themselves on raids, other than by letting Enchanters Theft of Thought their mana pool.