Making a kit for panther NPC

I was in the mood to start a new game again and wanted to be a druid, but I wanted my druid to have an animal companion with her as well. So I started making a specialized kit based on the monk class for my little kitty. This is what I've come up with, and if you have any comments don't be shy. I'm mostly wondering if it is well balanced.

The panther will be an actual full fledged NPC in my party and not a sideshow character like a familiar or summoned creature. If anyone's interested I could try to release it publicly, but I don't have much experience with WeiDU and some things are a bit clunky. Because of how the Create Item in Slot-effect works I'm forced to make the attack items movable because they have to be unequipped and equipped again to work for some reason. This also means that the panther can actually equip any weapon a monk can, contrary to the description. Personally I don't care - I will play it as I intended it - but others might find it immersion breaking.

- The panther has three types of attacks that improves with levels, Slash (1d8 slashing), Ram (1d4 blunt), Bite (1d12 piercing)
- Can become specialized in Short Swords (Slash), Club (Ram) and Dagger (Bite)
- The panther can make 1 unarmed attack per round; it gains 1/2 an additional attack every 3 levels (except bite which is always set to 1 APR).
- As the panther increases in levels, the damage its claws and bite inflicts does as well:
Level 5: +1
Level 10: +2
Level 15: +3
Level 20: +5
- A panther's natural armor class gets better as it goes up in levels. Its armor class starts off at 9, and then decreases by 1 for every 2 levels.
- Stunning blow, once per day. All attacks in the next 6 seconds force the victim to save or be stunned. NOTE: this special ability automatically modifies a panther's normal attack, no targeting needs to be done.
- Roar, once per day. All visible enemies must save or run in terror for 3 rounds.
- Panthers have the Deflect Missiles ability. This gives them a -1 to their AC vs missiles for every 3 levels.
- The panther gains a +2 to save vs spells
- A panther moves at +2 move
- Immune to feeblemindness
- 5th level: Panther's claws and bite are considered +1 weapons. Ram attack can knock an enemy unconcious
- 8th level: -1 to speed factor
- 9th level: +1 to all saves. Immune to blindness
- 10th level: Claws and bite are considered +2 weapons. Bite attack critical hit chance improved by 1
- 11th level: Immune to charm and confusion
- 12th level: Another -1 to speed factor
- 14th level: The panther gains 3% magic resistance per level (ie 42 at 14th level)
- 15th level: Claws and bite are considered +3 weapons. Slash attack can cause bleeding wounds
- 20th level: Claws and bite are considered +4 weapons. Immune to non-magical weapons

Disadvantages:
- The panther cannot wear armor
- A panther cannot use weapons