Ninjas:
Advantages:
- Cheap to recruit and would have their own armour
- Had a wide variety of weapons and techniques
- Often worked for money or close family ties; no diplomacy required
- A rather bizarre depiction of them is famous across the Western world (and probably the Japanese one, but I wouldn't bet on it)
- Stealthy, useful for spying, sabotage, and assassination
Disadvantages:
- Their armour, if they had any, was of bad quality, and with most of them their experience reflected their price
- Weapons were impractical and the techniques required more thought than a fleeing assassin would have given
- You'd better have more money than your opponent
- There is no record of their accomplishments
- It is impossible for them to be stealthy in the locations where they do most of their work
Gallowglasses:
Advantages:
- Trained from a young age and experienced through battle; had their own armour and weapons
- Many weapons suitable for the battlefield, including javelins, axes, claymores, daggers, and bows
- Always worked for supplies rather than money
- Almost entirely unheard of despite their legacy; will be underestimated by their ninja opponents
- Not that stealthy, but trained in wrestling and boxing, and to use their minds rather than fight as a unit
Disadvantages:
- Would often go to schools run by professionals for their training, would have tactics similar to those of others
- Often preferred one weapon; their kerns, responsible for their weapons, may not be available to give them a new one on the battlefield
- They had two kerns to feed. They'd want a lot of resources, especially if they were being paid to fight their own kinsmen, in which case they could charge ridiculous prices
- Who are they? What? No reputation.
- Not that stealthy
