I'm playing through the green guys events and trying to beat that golden armored chick is really fucking hard. with that combo special attack I can deal her a great amount of damage but when I exit out of the special attack mode the guy just sheathes his katana. As soon I unsheathed my weapon, I get knocked down on the floor, while while I'm getting up the boss regenerates it's health in an eye blink. And I don't have time to level up my katana skill because if you take just a little bit too much time it's too late for the event. Am I not getting something?

By the way, the game is really fun.

You need to upgrade your sword. The blunt sword available at the start of the game is really weak. Go to the smith in town and have him work on your blade. You might have to do a few playthroughs to get a good weapon.

You should be able to find a sword and spear with 30 strength; upgrade them with durability.
Use stab stab or jab jab techniques as quick strikes that move you forward seem not to be able to be interrupted.
In fact there is a good technique though i can't remember it off the top of my head that allowed you to basically flip on backwards out of range.
If all else fails use hand to hand, it surprised me that at the start of the game i could kick grab fast punch Hard punch my way through basically anyone (I got up to 33 kills before i went wtf i want to use a sword cause this is OP).
Also keep food meter at 100% before all battles.

My preference is the spear due to reach and the number of attacks that are simply you continually jabbing them in the face without them being able to get close enough to fight back.

You must farm money and junk weapons in order to grind your weapon to a good attack level. I spent my first day with the game doing this to get a Koutetsu ( a GOOD sword from one of the DLC bosses) and leveling it up to Attack 410+. I also spam the footsweep with follow up stab (while blocking, Forward+hard attack, then weak attack on the fallen foe) for easy kills.

Even on "easy", the game is very hard to finish without an extreme investment in upgrading weapons.