So, I somewhat agree on dragoon needing something. Any class that has sustain can beat it, and if you understand the mechanic of jump, it can actually be used against you. It's remarkably stamina heavy, but if you have to put points into the most useless stat just so you can still run after using 3 skills then it's remarkably bad. Dragoon isn't terrible. But it is on the lower end of the spectrum.
If we're talking about the best solo class, it's hands down ninja. I realize you're speaking from when you were playing this map, but dragoon is no longer the class of choice for solo play. Also, any class with a mobility skill with a bard can catch you as a dragoon. With the way current meta is being played though, dragoon can not kill other classes in a 1v1 (Besides ranger and like... that's it). It's melee damage isn't enough. It's mobility and control are good, but it doesn't do enough in a 1v1 anymore.
Yeah you can jump out of most situations, if you managed you stamina well and the other isn't playing a class with dots or a way to close distance (Disc can flying kick then force pull pretty easy, ninja can grappling hook and has a bow etc.)
Honestly, I hate dragonsmash. It's an entirely pointless skill that does nothing for the class. It either needs to do more damage, or be replaced with another skill. Piercing strike is just bad. (25% of weapon dmg? Terrible)
Slows in general have been nerfed to the ground. Sprint Jumping makes slows not nearly as effective as they used to be (I'm not entirely sure on this one though, but I've found every slow that used to be good terrible) and since spear is a cast, it makes it so that if their just on the range of your spear, you won't be able to get it off. I get the warm up for spear, but I don't think impale needs a warmup.
And if you're say that you shouldn't compare DK to dragoon, then you don't know the current meta at all. The meta is not, "Get in get out" It's, 'Get in and cap the Castle" and a DK doesn't need the ability to get out of a town after raiding it. It's a broken class. Becuase DK with any class that gives it mana with basically be able to 2v3-4 a town somewhat easily. Not exaggerating either. If you think a dragoon can jump in, do a bunch of dmg and jump out of a fight with a DK in the there, then you're wrong. If the dragoon is targeted by the DK, if he tries to jump out when low, then he's going to die if the DK know's what he's doing.
Not only that, but over half of the dragoon's skill set aren't viable in most fight due to stamina costs and just generally be bad. Dragoon's damage is very underwhelming compared to the rest of the meta at the moment.
I'm not sure what the class needs, but it does need something.