Yasuo is acctualy most played champion who need crits. In bronze nobody ban him and if he's on mid he has very good chance to feed himsel. But when he hit the Garen Yasuo don't much chance to kill somebody in teamfight. And if Garen got a Thornmail Yasuo can do nothing + he deal damage to himself.

Armor runes are better choice if Yasuo is on mid beacouse enemy team hasn't much chance to get any AP champion (only Junglers like Evelynn and Elise, Toplaners like Singed, Teemo or Rumble, and supports aren't very powerfull only supports like Karma, Morgana can change your item or runes choice.

Masteries to play Garen don't need be defensive beacause he get much armor from runes and his base stats. So you can focus to damage. But the best masterie are same as for the Singed. This is Cooldown reduction,Health,Armor and Movement speed.

OFFENSIVE + DEFENSIVE ITEMS

• Sunfire Aegis+ Thornmail are defensive and too offensive items beacouse Sunefire cape deal damage to nerby enemys and Thornmail reflecte and return percents of the damage.
• And if you want fight any AD carry, AD carry has not got chance to kill you and when is this ADC stupid he kills himself.
• In game thornmail is good againist Tryndamere,Yasuo and GP.

OTHER ITEMS

• This is sigle item for damage and in combination with armor penetration and health is nice offensive on Garen.
• This item may be usefull in teamfights cuz hes active slow all nerbys enemys and it has armor + health.
• Banchee can block Yasuo's first auto attack or torrnado.
  When this items block torrnado he can't use U.