To EarlofEtheria, about your Eyes of Garyx.
When submitting an item, I would suggest that you make it as inclusive as possible. A Garyx themed item is obvioulsy about dragons, but it doesn't mean it has to be restricted to dragon disciples.
In this case, restricting the sickle to Dragon Disciples kept it out of the hands of full Sorcerers who frankly do not need an item this powerful. Druids, Clerics, and Favoured Souls could be added to to the list, or really all classes except Sorcerer and Pale Master. To avoid bloat Dragon Disciple was the listed restricted class.
There is staggering number of 8 malus properties on your item (some of which the guidelines clearly suggest you keep away from), plus 3 use limitation restrictions on your item. I get it that the idea is to lower the cost of the item, but that is too much. Nowadays we try too keep away from such items. You should tone down both the bonuses and maluses instead.
Dragon Disciples who remain dual classed Sorcerers sacrifice a lot , losing out on 8th and 9th level spells (or even 6th and 7th), and a far slower progression of magic. The design could be trimmed down to only a weapon or only a caster's aid, though I worry if it will be desired enough as a weapon (being a sickle). Dragon Disciples gain martial bonuses which makes the former important to the archetype. I admit that the maluses stacked up when adding those spell slots in an effort to maintain desirability, while trying to keep the idea of an regal and unwieldly mantlepiece (that players would still want to fight with, even with a -2 to hit and damage). With how the item's last paragraph is written, they don't need to be gold and stone at all, something to consider.
While I do like the idea of items that could only be used by a given alignment and its opposite (a series of items could be devised around that theme), I find greater issues in restricting said item to a class that absolutely does not need help. I would suggest you instead focus on weaker classes such as grimetrekkers or monster hunter.
The Eyes of Garyx were conceptualized for those who wanted to play as a Sorcerer Dragon Disciple, a PRC combination with no specific reward for going Sorcerer 10-15 (where sorcerers are supposed to be dominating the class' population, the
minimum in sorcerer is often better taken and multiclassed if not ignored for Bard and Hexblade). If there was a Dragon Disciple restricted item, I believe it would benefit sorcerers.
Thematically the powers do not make much sense either. Garyx is a dragon deity of fire and destruction caring little for his followers. It's on these themes the item should revolve around. Magic and divine damage, or even just bonus spell slots are off the mark here. Perhaps you should consider an item dedicated to Kereska, a draconic goddess of magic instead.
Garyx is also worshipped by rogue Gold Dragons and Druids, believing in the Renewal (unsupported Domain) brought from fire's destruction, hence some duality or benevolence from their followers is plausible. I'll reconsider the damage types and theme, though the spell slots were certainly my vision behind this.
Do note. Work has been done very recently to make sure that all casting classes have a fair amount of spell slot items in the treasuries. Sorcerers certainly do not need more and it is highly unlikely we'll add more. But if you still feel like suggesting one anyway, my advice is to put it on an item type that will force a sorcerer to make a choice. For instance, if an amulet already exists that gives a level 4 spell slot, make an amulet that also gives a level 4 spell slot but with different accompanying bonuses. This way you give customization options to players without adding to the powercreep of mid/high level casters.
As described earlier, the choice to remain invested in Sorcerer as a Dragon Disciple is one often hard onto impossible to swallow with the lack of PRC spell progression. The high tier spell slots of the Eyes of Garyx only reward those who consciously maintain the Sorcerer class like 10 Sorcerer/10 Dragon Disciple over something like 9 Cleric/1 Sorcerer/10 Dragon Disciple.
Also, keep the bonus spell slot to lower levels. I would not exceed 5th level personally, and that is stretching the limit already (but that's just a personal opinion, don't read that as the official DEV stance).
I doubt it would be an issue, should it remain restricted to Dragon Disciples. Perhaps such a non-issue in that we may never see the spell slots utilized except by Sorcerer/Rogues?