About the Skill:
Bushido is the main skill of the Samurai, and embodies the very essence of honorable combat. With it and the Book of Bushido (purchased from Tokuno Islands scribe NPCs or looted from Ronin), the Samurai can perform a variety of special abilities that mostly are defensive in nature - but can be used to quickly and honorably defeat the toughest of opponents.
Samurais receive several passive benefits based on their Bushido proficiency.
A character with Bushido as well as the Parrying skill will be able to block with a weapon, though their defense chance with an actual Shield is lowered as they progress as a Samurai. Chance to block can be calculated using the formulas on the Parrying page. Bushido also offers the only method in the game to entirely avoid direct spell damage: The Evasion ability.
A Samurai with 50 Bushido or above may activate the Perfection system by honoring a target creature. This grants a damage bonus dependant on consecutive hits.
Whirlwind Damage Increase
Bushido gives a damage bonus to the Whirlwind special move. This bonus is capped at 100. The bonus is determined by the following formula: Damage\;Bonus=(Bushido/60*Number\;of\;opponents)^2
For example, if you are using a weapon with Whirlwind on it, and you are surrounded by 4 enemies, and have a Bushido skill of 90, the additional damage you do to each of those enemies will be 36 points of additional damage.
At 120 bushido, a whirlwind receives the max bonus when surrounded by only 5 enemies. At 100 bushido, a player must be surrounded by 6 enemies. Players must have at least 66.6 bushido to maximize this bonus (It would, however, require the player be surrounded by 9 enemies).
Reduced Special Move Mana Cost
Special move mana cost can be reduced by achieving a combined total of 200+ points in several combat/magic skills, including bushido. A full list of applicable skills is available on the special moves page. When the combined total of these skills is 200-299, mana cost is reduced by 5 mana points, and when the combined total reaches/exceeds 300, the mana cost is reduced by 10 mana points.
At 90 skill, it becomes possible to use Bushido in place of Animal Taming for the purpose of controlling and riding Lesser Hiryus.
How to train:
0 - 30: Train at NPC Samurai in Zento.
Note: If you are on a murderer, you will have to use a Soulstone or get some jewelry to raise your skill to 25. You cannot train Bushido from below 25 skill.
30 - 60: Cast Confidence.
60 - 75: Cast Counter Attack.
75 - 105: Cast Evasion.
105 - 120: Cast Momentum Strike.
The Bushido required to successfully cast each ability 50% of the time is presented on the Formulas and Game Mechanics page.
The NPC trainer for bushido in Haven will train your skill up to 40, and you can train with accelerated skill gain in Old Haven if you accept his quest. Do not accept the quest until after you have bought your skill; you cannot buy skill while on an accelerated gain skill quest.
The best training method I've found is to train the skill up from an NPC and use jewelry to get yourself to 50. Then use Lightning Strike on your opponents until you reach a real skill of 50; remove your jewelry and continue to use Lightning Strike until you reach 110. At this point switch to Momentum Strike. Lighting Strike will, however, take you all the way to 120 if you prefer.