What do "black/purple" colored Killer Techniques do?

I understand no japanese, all I could think of was some passive abilities, but it's completely made up

Then I thought it was something like "useless" technique, but why would you be able to teach them to you players then? Help please :3

It is passive abilitiesXD
like Aphrodites shoot force increases the chance for a goal for the whole team.

What is tsunami's?

When you are winning, players on your side get a bonus with technique (this affects everything that you get a left and right choice with...I don't know how to explain orz); when you are loosing, technique goes down. The effect is greater when there is a larger difference between scores.
Fudou has a similar skill but his only apply to himself.

Thanks lad :3