It is said that they are trained in using their school's signature heavy armor, allowing them to ignore the Cumbersome quality of the armor. Nevertheless, the armor that they are getting does not have the cumbersome quality. So is there a mistake or a motivation to get one? XD

You can get the Plated Armor that has the Cumbersome Quality if you want +1 Protection and some literal durability for your armor. It is 40 koku and Rarity 7, so order your GM a pizza if you want it.

1 hour ago, Thalenus said:

It is said that they are trained in using their school's signature heavy armor, allowing them to ignore the Cumbersome quality of the armor. Nevertheless, the armor that they are getting does not have the cumbersome quality. So is there a mistake or a motivation to get one? XD

There is a motivation to get one - because you can use plated armour more effectively. However, it's essentially a freebie 'extra bonus' - the real 'point' of Way Of The Crab is your ability to tank unparried criticals.

Question 16 also allows you to acquire Plated armor (rarity 7) as a gift or claimed in battle (as of the 3.0 update).

You may still want to order pizza for your GM.

On 5/12/2017 at 0:19 AM, ubik2 said:

Question 16 also allows you to acquire Plated armor (rarity 7) as a gift or claimed in battle (as of the 3.0 update).

You may still want to order pizza for your GM.

Thanks for the tip

Unless you are expecting to roll around in war setting, I would rathet grab Lacquered Armor - it has one less resistance, but it is Ceremonial Wargear, so you could make a case for it being appropriate for more social situations, especially if you flavor it as a gift/a reward for service (because if someone asks you why you are wearing armor around, you can tell them how awesome is this gift from the mother of your fiance and you are wearing it all around to honor them because they are so awesome, etc - + Ceremonial tag has it kinda included).

It won't help you use the ignore Cumbersome quality...which is imho why it should just ignore first instance of Cumbersome on your person, be it from armor, or from weapons.