A few months ago I came up with a theory about why Pearl has a weapon despite being made to be a servent. The original theory was that all Gems wether they're soilders or civillians need a method of self defence incase of danger, and since Pearls powers can't be used offencively she was given the power to summon a weapon.
After a mix off watching new episodes and general thinking I don't think this is the case anymore. Firstly ,if you look past the Diamond tyranny and the culling of unfit Gems, Homeworld seems like a pretty safe place to live. Theres no dangerous wild animals, there's likely many gaurds and defence robanoids.
The only fit/law abiding Gems that get exposed to danger are soilders, those in charge of collonization (i.e. Bismuths and Lapis') and those sent on special missions (although they're given escorts and Gem tech). Pearls, Zircon, Sapphires and the like are not likely to be in danger (unless they upset the Diamonds).
Speaking of Zircon, she even said that if her mistress was under attack the worst she would do is cry in alarm "Watch out my Diamond!"
So whats my new theory?
Well, remember Holo-Pearl? Well they can create weapons like spears, swords and axes out of nothing too. Holo-Pearl and their weapons are also tangible as well just like a Gem weapon.
My guess is that Pearls spear started life as a hardlight hologram just like the Holo-Pearl summons. Now if you remember, Pearl started with normal swords but used a spear sometime after Bismuth joined. So I think that Bismuth may have took Pearls holo-spear and transformed it into a more stable permanent form. After all, the fact that they didn't question Bismuths ability to upgrade weapons implies that it may not have been the first time she's done it.
This means that thoereticaly Pearl could summon any weapon she wants, althought they won't be as strong as her Bismuth enhanced spear.
Now, how exactly can Bismuth upgrade summoned weapons? No idea. I you have any theories about that please tell me.