The thing about Spinel...
Steven Universe movie spoilers but HUGE REALIZATION
AVOID SPOILERS BELOW, I CAN'T DO A READ MORE BREAK ON MOBILE
I had been so confused about a lot of things with Spinel.
She stood still for six thousand of years. Doing nothing. Before that she simply played with Pink Diamond and entertained her.
Suddenly she faces the Crystal Gems and she's a beast. She has amazing combat capabilities, top notch scythe profiency, somehow was able to acquire said scythe and injector with seemingly no one blinking an eye, the Diamonds not even aware of this. Despite thousands of years of active combat experience by the Crystal Gems, this cartoony babysitter was able to easily dispatch them all.
For the longest time I tried to think of how this was possible and said to others, "Imagine if she DID have training and experience, she'd be amazing."
Then I realized. Any gem can be amazing in their skills, have all the knowledge they need the moment they burst from the ground.
Spinel already HAD this knowledge. She's not just a babysitter and entertainer for Pink Diamond! She was created as a GUARDIAN. Explaining why the Diamonds were okay with Pink being left alone for extended periods of time so long as Spinel was with her. If Pink Diamond was ever in danger, Spinel, even as her former self, was fully prepared and equipped to protect Pink Diamond at any cost.
This meant combat expertise, weapon proficiency, full access to any and all weapons and ships. This little gem probably had more access and permissions than most gems because she was the personal bodyguard of Pink Diamond!
Spinel is a BEAST, she was created to be! She is the Secret Service agent equivalent to Pink Diamond!
God, I love Spinel