Okay. How about, and stick with me here, a nature master/user/lover. And no, not like, elements. I mean the real deal.
Follow me on this...
So you'd start off with a little pet bush or something. It has some thorns or whatever. It's not very cool.

However! As you progress you get even crazier things; Like some vines that whip and slash. Maybe some poison leafy plants with big ass prickers and that poison the enemy. AOE, vines everywhere. Pure mayhem.

"but what about desolate places and caves and dungeons?" you might ask. simple. Fungi! Oh yea.
"Okay, deserts?" CACTUS... and other succulents. How brutal would that be. (think like cactuar).
(Gotta stay in the realm of what's believable) (ha)
Now by the time you get to max rank you would just have this giant red wood tree thing that just explodes out of nowhere and collapses on the guy. Total annihilation. And maybe treants. How magical.
You could even fashion these neat, little wooden traps and weapons. Nice.

Don't rip me apart here. I was just reading this thread and looked out the window and was like OH SHIT.

P.s The plants would be the pets being asked for. Idk

FFXIV: Going Green.