Warrior Mini Boss:
You first encounter these guys in the City. They are massive shield warriors with swords. They have a few basic attacks: a slash, a shield stomp, and a beam attack. Mostly this boss takes patience and reading his movements. When he throws his arms back wide, he is about to do an overhead sword slash. It's easy to dodge this. He'll do it when you're medium range from him. When you are closer, he will pound the ground with the edge of his shield, which does a small splash of damage. This is one of his vulnerable moments where you can slash at his face, as it's the only weak point he has. Give him three slaps and back off. Once you knock him down about 1/2 way, he'll begin to use his beam move. The "read" for this attack is a motion that looks like coughing. His move starts out as his alignment, then switches to the opposite alignment, then back sweeping up and down each time. Getting too close interrupts this and begins his shield pound, but if you can jump in when he's using his opposite polarity, you can score some extra hits and interrupt the beam attack
Smite does a small amount of extra damage, and I don't recommend charged attack as the close range of it can get dicey. Beam doesn't work too well, but it's possible to use it. Bombs will instantly kill him (only the first one of these is near a bomb dispenser). He's not very difficult, and just requires time to kill him without getting hit.
I have a quick way to deal with this (too bad i don't have any camera to record it):
-It is simple to reduce its heath to 1/2, just get close enough and slash his leg (low slash). When he begins to stomp to shield, get back and repeat.
-The last is easy as above, just slash his face with opposite polarity when he is attacking with a beam.