Martial Artist - Swordsman
With their fighting style based on Trunks', Swordsmasters are designed to be the powerful continuous 1v1 damage dealers, while having plenty of tricks and combos up their sleeve to remain relevant in PvP. Unlike Fighters, it's not easy to completely screw up a Swordsman's build. Whether you go for a pure energy, hybrid, or pure physical build, you'll find there's lots of ways to make a Swordsman viable. Just remember Swordsmen are primarily geared towards 1v1 battles, and need alot of investment before they see their potential. You have some options at lvl70 for AoE farming, but generally AoE is their weakest point.
I will not give you a "perfect build", but rather the info you need to make one yourself by explaining each skill. Some of this will be copy-pasted from my Fighter Guide, with info adjusted where necessary. Skills that work well on Fighters may not work well on Swordsmen and vice versa, and I will highlight those differences in this guide.
Plan your own Swordsman Build here: http://tools.dboglobal.to/dbo_skill_calculator/?tool=Skill-Calculator&class=Swordsman
======== Martial Artist attacks ============
Double strike is a move you'll have by default. It's pathetically weak, but it'll help you level up. Since it's a very simple and fast move, it's great for finishing off those pesky enemies that just barely hung on with a sliver of LP.
I can't recommend maxing this, but putting some points into this early on can speed up the leveling process a bit! Just skill reset later.
No words can describe how important this technique is. It'll stun your enemy outright, stopping whatever they're doing(Great for stopping a mob/player who's charging a skill) and giving you free reign to ruin their life. I'm not sure I've ever seen a successful Martial Artist that hasn't maxed this skill. Use RP to prolong the stun by 3 seconds, or shorten the cooldown so you can spam it again. Don't assume you don't need Kidney Shot because you're geared towards PvE. It's quick animation makes for good DPS even against stun-immune bosses.
ROCK PAPER SCISSORS
The skill that's almost Wolf Fang Fist's equal. Good for finishing off enemies hanging on with a sliver of LP just like Double Strike, except it's a bit stronger and slower. At maximum level this move will confuse enemies for 1 second, which can disorient them a bit. But that'll lower the move's damage and cost you another SP.
If you want a slightly weaker Wolf Fang Fist that costs 1 more SP, but is spammable thanks to a 5 second cooldown and does max damage from all angles, then level this to lvl7. Otherwise, keep it at lvl1. Maxing it makes it a good move interruptor, but you're losing out on damage and raising the EP & SP cost. You can probably use knockdowns and Scintillation to buy yourself time instead.
WOLF FANG FIST
Compared to most of your sword attacks, this move isn't that great in comparison, especially seeing how it calculates from glove power and takes 6SP. That said, it still does VERY respectable damage, especially from behind. A physical swordfighter will mostly rely on Multiple Sword Slashes with this being their secondary melee move.
As a physical Swordfighter powerhouse, this move is highly recommended. It's not bad for a hybrid persé, but they may want to consider SP for utility or Sword Slashes instead. Energy Swordfighters have nothing to gain from this. It's also great for leveling any Swordsman.
As the name implies, this is your fastest attack. Possibly the fastest connecting attack in the game. The moment it's used, the stun will immediately activate as you fly towards your enemy into melee range. It's great for interrupting skill charges, getting to your enemy instantly, stopping your enemy from fleeing, ignoring movement speed debuffs, getting a match's first strike, and as secondary stun.
Arguably this move is more important than Kidney Shot, no matter what build you're rocking. It's an absolute must in PvP. Energy and PvE/leveling Swordsmen don't NEED to max this, as it only increases stun and cooldown time, but I'd still recommend lvl1 at least for utility.
It's the ultimate luring move! It's damage is negligible, but it is super fast and has fantastic reach. Great for baiting that pesky boss/ultra out of his group of supers for a more fair 1-on-1 battle, or finishing off that annoying fleeing enemy with a sliver of LP, or luring an enemy you need to kill from that field of enemies you DON't need to kill.
For any Swordsman busy doing anything in PvE, I'd recommend this. Swordsmen want to engage in 1v1 battles as much as possible, and luring enemies from afar with this will help significantly. Just don't upgrade Tunnel Slash. If you want damage, spend 2 more SP to get a "Stronger Energy Barrage" instead.
Crappy damage with crappy explosion range. That said, it's usefulness lies in it's knockdown. It's your fastest attack that inflicts knockdown, leaving little time for enemies to interrupt. Because it has no afterlag, it also leaves time for you to do a followup attack! It's damage may suck, but together with Energy Recovery this gives Swordsmen alot of combo potential.
For any PvP Swordsman who wants to juggle knockdowns, get this at lvl1 and Energy Recovery at lvl4. Don't bother upgrading it.
It's your first possible move with very reliable and decent fast damage! Perfect for lending ranged support(without luring a dozen unwanted mobs to you), finishing enemies off, and in some cases luring them. It has a longer animation than Tunnel Slash, so be aware that you're giving your enemy a chance for free damage while using this. Because of that, unless it's for finishing someone off, try NOT to use this in PvP.
A very decently strong and fast move with no cast time. Energy Swordsmen may find much use in this when they need ranged damage. Same for Hybrid Swordsmen, though they should probably leave it at level 1. This move won't get you any unwanted aggro like most of your other energy damaging moves.
Majin Vegeta's move on Majin Buu. This move is the strongest non-HTB spiritual skill in the game when maxed out, and a Martial Artist's first TRUE AoE(Area of Effect). I'd shudder to think of the damage Turtles would achieve with this thing.
Don't let the damage go to your head, though. The move severely lacks in utility. You'll be floating for 4/5 straight seconds in 1 spot with a rather small AoE. Mobs will be beating on you while you're doing this, you're wide open to stuns or curses, and ranged mobs will probably dodge it entirely. You could stun players and then combo into this move, but at that point, throwing out 2 sword slashes would benefit you more. Worse so is that unlike a Fighter you have no Ghost/Solar Flare, and less DEX to set this move up safely.
Even though a Swordsman could hit even harder with this than a Fighter(FOC = Energy Crit), they lack any utility to actually use this in the first place. If you want to play AoE on a team, then you can have others lure enemies right into the explosion, but otherwise this is just too situational to upgrade.
STRONGER ENERGY BARRAGE
This move is basically a slightly weaker and slower Energy Barrage, except it has a small AoE and the ability to knock down! Perfect for chaining with Energy Barrage for distance support, finishing off a group of enemies that survived your AoE, or knocking people down from a further away than your Kamehameha can.
Energy Swordsmen can max it out for lending better ranged support together with Energy Barrage, but getting it at lvl1 for the knockdown is good enough. Unfortunately this is one of your only reliable AoE finishers, and it's mediocre at best. If you HAVE to try AoE as a swordsman, you'll need this, but for most this is just a luxury beyond it's knockdown chains.