Salutations, and greetings! I read the recent update for the upcoming art that will be present in the next chapters, therefore, I wish you the best of luck!
For the scar thing, I am a little iffy upon putting this out there, but here it is!
Perhaps a scar that extends from the right side of the next, just slightly above the collar bone, and traces downwards either to a point on the character's arm, coming to a stop just at the tip of the elbow-
OR-
The scar could weave itself from above the right collarbone onto your character's back; perhaps making it's way to the hips, and maybe further on until the thigh, or stopping at the hip-bone.
These are the two ideas I can think of for the panther form and the character's original form! Other ideas, such as for the armor, include this:
Thin steel plates that were handcrafted, shrouded in a sheet of the character's favorite coloured of dyed leather and maybe some decoration. Maybe your character has a bag of some sorts to carry the armor in, equipping these pads before they're able to transform. In frantic, sudden situations, perhaps there could be something magnetic on the character's clothes so the armor may be attracted to it? That idea is quite palpable!
That finished up the idea list. Maybe there could be scars that are merely visible to the eye around the panther's face, or some other details, but these are simply ideas- but there you go!
Have a wonderful evening! I dunno if it's the same to you, but hey! Positivity!