Mount&Blade/Skills

Personal Skills
These are skills you or a companion can possess. They don't affect the party.

Ironflesh
Ironflesh has no use beyond increasing hit points. At early levels it isn't always very important, but as you fight tougher enemies every bit of protection helps.
 * Base Attribute: Strength
 * Maximum Level: 10
 * Effect: +2 HP per level

Power Strike

 * Base Attribute: Strength
 * Maximum Level: 10
 * Effect: +8% melee damage per level

Power Throw
This skill is needed in order to use more powerful throwing weapons, so don't ignore this skill solely based on its meagre damage increase.
 * Base Attribute: Strength
 * Maximum Level: 8
 * Effect: +10% thrown weapon damage per level

Power Draw
This is required for the more powerful bows, and is overall a valuable skill for making archery less difficult. You can put up to four points in this beyond the power draw requirement of the bow (if any).
 * Base Attribute: Strength
 * Maximum Level: 8
 * Effect: +14% bow damage for each point (up to 4 plus Power Draw requirement of the bow)

Weapon Master
This skill allows you to continue using weapon proficiency points after you have passed the normal cap, and also lets you raise your proficiencies more quickly.
 * Base Attribute: Agility
 * Maximum Level: 9
 * Effect: raises the proficiency points cap, makes raising proficiencies easier

Note that this cap is only for the purpose of spending additional proficiency points; using weapons in combat will continue to raise your skill regardless of what the proficiency cap is set at, but it will do so faster at higher levels of Weapon Master.

This skill is useful if you like boosting your weapon skill each time you level up; if you're content to improve your proficiencies by fighting you won't need this.

Shield

 * Base Attribute: Agility
 * Maximum Level: 8
 * Effect: reduces damage to shields by 8% per level and improves shield speed and coverage.

Athletics
This isn't very obvious early on, but with a few levels it will start to really take effect. This skill is made less important by having a horse, but it's still a useful backup if you lose your horse or if you want to fight on foot. Also it is useful during sieges and tournaments, where a horse might not be available. Note that the combined weight of your armor and equipment will reduce the speed bonus your Athletics skill grants.
 * Base Attribute: Agility
 * Maximum Level: 8
 * Effect: Increases running speed.

Riding

 * Base Attribute: Agility
 * Effect: Increases riding speed and maneuver, allows riding of more difficult horses.

Horse Archery
This works by widening the aiming reticule less significantly when moving. This is a very useful skill for archers, but useless if you are melee-only.
 * Base Attribute: Agility
 * Effect: reduces penalties for using ranged weapons on a moving horse by 10% per level.

Trainer
Experience points are not given to party members that are fully upgraded. If multiple companions have this skill they will each help train party members.
 * Base Attribute: Intelligence
 * Effect: Every day at midnight lower-level party members gain experience

Experience gains per level are as follows:

Inventory Management

 * Base Attribute: Intelligence
 * Effect: Increases inventory size by 6 squares

Party Skills
These are skills that each character individually possesses, but they are applied to the party as a whole.

Looting
Increases the amount of loot obtained by 10% per skill level.
 * Base Attribute: Agility

Tracking
This skill makes tracks appear on the world map, gradually becoming more accurate and providing additional information. At level 1 the tracks indicate party movement, but little else. As levels progress the accuracy of party size predictions and hours the tracks remain visible for increases. Tracks will also gain colors, allowing you to easily follow a particular path regardless of what other paths it crosses.
 * Base Attribute: Intelligence
 * Effect: makes onscreen tracks appear and gradually become more informative

Tactics
Before each battle your Tactics score is compared to that of the enemy leader, and this determines how many men each side has at the beginning of the battle.
 * Base Attribute: Intelligence
 * Effect: Every 2 points to this raises your battle advantage by 1.

Additionally, if you choose to send your men in while you stay back or are knocked out during battle this skill will have an effect on the aftermath losses.

Path-finding

 * Base Attribute: Intelligence
 * Effect: Increases party map speed by 3% per level.

Spotting

 * Base Attribute: Intelligence
 * Effect: Increases party sight range by 10% per level.

Wound Treatment

 * Base Attribute: Intelligence
 * Effect: Increases party healing speed 20% per level.

Surgery

 * Base Attribute: Intelligence
 * Effect: Each point adds a 4% chance that mortally-wounded troops will be knocked out rather than killed.

This skill is quite useful for giving your troops the best chance you can to reach higher levels and become effective fighters. It also lessens the annoyance factor of spending top dollar on some new, high tier troops (eg: Hired Blades) only to have a significant fraction of them be killed in their first battle.

First Aid
This skill is very useful. Companions and your character will heal a little between battle waves. Note that this only heal up to the level of health before you entered battle, so if you go into battle with 60% health you can only heal back up to that level and no further.
 * Base Attribute: Intelligence
 * Effect: Heroes regain 5% per level of hit-points lost during battle

Engineer
This skill is very useful if you want to besiege castles and/or improve fiefs, but it has no other purpose.
 * Base Attribute: Intelligence
 * Effect: build siege equipment and village improvements more quickly (-5% on time and price to build improvements)

Trade
The Trade skill reduces the cost penalty applied to buying and selling. See Trade for more details.
 * Base Attribute: Charisma
 * Effect: reduces trading penalty by 5%

Leader Skills
These skills affect the party, but only if the person with these skills is the party leader.

Persuasion

 * Base Attribute: Intelligence
 * Effect: Helps you make other people accept your point of view. There is a random factor involved in determining how successful you are.

Prisoner Management
Useful if you want to take prisoners, useless if you don't.
 * Base Attribute: Charisma
 * Effect: increases prisoner capacity by 5

Leadership
A very useful skill to have! The higher your Leadership the more men you can lead into battle. You'll probably want to put a point towards Charisma every other level or so, and a point towards Leadership every chance you get. Increasing your Renown will also raise the party size cap.
 * Base Attribute: Charisma
 * Effect: increases party capacity by 5, boosts morale, reduces troop costs and wages by 5%