I think that was Fromsoft’s way of saying “the sorceries that these staves boost can take… a while. So we’re going to make these few scale based off of Dex to encourage players to put points into Dex to speed up those spells, and also to make sure there are enough Dex/INT staves available for that build.”

Not everyone wants to be a STR/INT build. Some want to be DEX/INT builds. Also, the spells that those staves boost tend to be on the slow side, so the DEX scaling makes sense for those because of the cast speed increase.

Makes sense that the Staff of Loss and Carian Glintblade Staff share such similarity, seeing how the former looks like just the latter with less coloration and the glintstone missing.

Not a staff you should have at req. only because it's meant for min-maxing INT builds. At 80 int it's got the 2nd highest sorcery scaling, so this is your go to staff if you want to not burn through FP and still deal decent damage. The boost to full moon sorceries isn't any more noticeable than the boost in damage you get from Lusat's, but the weapon art deals damage that scales with the sorc scaling so you can really catch someone lacking and oneshot them with the magic oreo

The way the highest INT scaling staves have always worked is that they start with a lower spell boost at lower levels compared to other staves, but they have higher scaling. At level 68 INT, this staff does indeed become the best staff in the game.

It's because there are two types of stat scaling with glintstone staffs, front-loaded and back-loaded. front-loaded staffs get the biggest sorcery scaling increase from 40-60 int (carian glintstone staff is front loaded), back-loaded staffs get their biggest increase from 60-80 int. Carian Regal Scepter is a backloaded staff, so you haven't actually gotten the into the intelligence range that the staff truly benefits from. At 80 or even just 70 int this staff will perform much better than the max upgrade on the carian glintstone staff. There's a Reddit post called "Helpful Charts for Offensive Stat Scaling" that was posted to the Elden Ring subreddit that visualizes the stat scaling for most weapons in the game.

Yes, and then some. Since damage multipliers are multiplicative, you get a little extra bang for your buck, even if it only gives you around 1% extra damage.

I tested and it gives almost precisly an extra 10% damage (2539 vs 2308), so if you're using them a lot it might be worth it

The spin is really good. I feel like it rivals Carian slicer because of the poise damage. And besides there are more than enough memory slots for terra magica.

If you also use Winged Sword Insignia, a single use of the spin will get you the max damage boost.

10%

Tested on the trash mobs in Cave of Knowledge. Looks more like an 8% bonus.

Well, I looked at the actual values in the game code. It's 10%.

It's 10%, you also have to account for mobs absorbtion/defense.

put the staff on your left hand, duh