This post is just my opinion so try to read it with a grain of salt but I'm guessing that what skink is trying to imply is that having a manakete be able to defend itself in human-like form with a weapon is already a significant leeway. In reality they would not even be able to do that, to balance out being able to turn into a metaphorical nuclear missile. 

That being said, the rules were already bent for your character. But to have the manakete be even close to a human in terms of capabilities (without a dragonstone) would be pushing it. Some Magical tomes/staves/books even have effects that barely care about the wielder's stats (while being really useful regardless), that would essentially make your character a human... with dragonstone. It becomes a disconcerting amount of advantage given to your character (both combat and roleplay opportunities), but it makes the game much less fun for others as a result. 


That's how I feel about this. I don't mean to sound rude. I just think being the manakete is already very special and a privillege itself. More will only make the rest of us feel like background scenery (which will be the case once dragonstone is used... we've come to peace with that).