Ninjas are a subscription exclusive class. The Ninja is a fast, hard hitter that can turn their enemies into healing items. Unmatched in strength growth, a ninja can be a hard hitter for the entire game. For all of the strength a ninja gains, they eventually lose pace with soldiers and merchants in attack power due to their main weapon type (gloves) not adding attack power on its own.
The Ninja can equip cloth armors and glove weapons. Glove weapons are unique in that they all have an added status ability that has a chance to activate when a ninja attacks, and that they have no attack power on their own. Gloves can have a chance to inflict poison, curse, sleep, slow, confuse, soften or kill (instantly kills non-boss/player targets). Confuse and kill are currently restricted to unique gloves (Delicate Ninja Glove for confuse, Malevolent Gauntlet for kill).
Skill trees are the basis of leveling and customizing your character in NEStalgia. The skill tree menu unlocks at level 5 and at that point the player will be able to customize their character with the five points available. There are three ways to gain additional points:
Gain an experience level, which grants one point.
Progress through the plot of the game, which grants one point after completing the main quest connected to Verity's lighthouse and an additional point after completing the main quest connected to the Arctic's ice palace.
Spend 100,000 gold on a Greater Moon Blessing, which grants four points all at once.
As of v1.62 this allows for a maximum of 38 points to spend.
Spirit Fingers: Any ninja that wishes to maximize the chances of their glove's on-hit trait kicking in should invest as many points as they can spare in this branch.
Fair Fight: Later on in the game most battles will start with the ninja and their party being outnumbered, so this branch allows a way to get a quick and easy damage boost that can prove to be enough to defeat a monster in a single strike.
Pierce: The spell piercing is limited in use, due to a ninja's source of elemental damage being whichever enchant they choose. With that said, 5-Point can be quite handy, providing a source of high and (mostly) unblockable damage.
Ambush: Being able to turn a normal battle into one where the party gains first strike 5 to 10% of the time has it uses. It helps that Ambush is not connected to a different branch as well as that it is available as soon as skill trees open up.
Double Punch: The chance isn't a high one, but it is nonetheless a chance to inflict an additional 50% damage at no MP cost. In the long run, the 12% chance gained from this tree may prove to be enough to allow some enemies to be felled in a single round without the aid of a critical hit.
Blitz: This branch is of use to any ninja looking to contribute solid multi-target damage to a party. The cost per use is modest, but a ninja's naturally low MP pool can make FistFury seem as pricey as a wizard's fully powered Firewall, Blizzard or Tornado.
Soul Eater: Essence can be an effective way to maintain a healthy level of HP for party members and the ninja. As such, increasing the power of bottled essences without having to dedicate equipment and seed slots to +HEAL is arguably an effective use of skill points.
Extra Powder: Sometimes a battle calls for a ninja to take charge by... well... triggering an explosive charge. Making that explosion as big as possible is the sole purpose of this branch.
Lightning Fast: Ninjas are already the most agile class by a fair margin, so at first glance adding more agility would seem to be overkill. However, investment in this branch is the only way for a ninja to learn how to use NinjaNet, which can allow other party members a way to attack earlier than enemies that normally would have the initiative.
Retailiate: Much like Double Punch, this branch gives a ninja a way to tack on additional melee damage to an enemy. Some would pause at the requirement that the ninja dodge an incoming attack, but there are multiple ways to increase a ninja's evasion and/or decrease an attacker's accuracy.
Deft: Additional evasion is nice, and that bonus helps increase the frequency of retaliations off of missed attacks.
High Jump: JumpKick has an added chance of avoiding attacks as is, but if that chance isn't enough then points in this branch will increase those odds. As with Deft and other branches that increase evasion, points in this branch will increase the odds of a counter-attack via Retaliate.
Cunning: In spite of having solid natural intelligence growth, ninjas are still somewhat vulnerable to magic damage when compared to classes such as warlock or wizard. Points in this branch will not only work to lessen incoming magic damage, they will also increase the damage of Essence and add extra physical defense.
Trickster: Trick allows a ninja to confuse a single target at a fair MP cost (5 MP, half the cost of the Confuse spell that can be learned by wizards). Further investment in the branch raises the success rate, which is always good if confusing a target is a high priority.
Eschew: Yet another skill branch that improves evasion, making Smokebomb and Vanish even better at keeping attacks based on accuracy from landing. As expected, that extra evasion makes for a nice synergy with Retaliate.
Lone Warrior: Just as Fair Fight increases physical damage when there are more enemies than allies, this branch increases overall defense. It's available early on and doesn't require investment in any other branch, so points placed in this branch can prove a good way to reduce the amount of damage taken in the early rounds of a battle.
Abilities are skills that the player can use both inside and outside of battle. These abilities will either be bought on the skill tree using skill points or will be learned automatically once the player hits a certain level. Soldiers currently have no abilities that can be used out of battle.