I can't fit the words on the pic so here we go.
1. When Assasin was born, his eyes were devoid of pupils. Therefore, his parents thought he was blind for a very long time. "But Daddy, I can clearly see you're purple!" "You hear descriptions of me all the time, I don't know why you continue with this joke, it was funny once." The other thing about baby Assasin is that he didn't have the silver gradient on his spines until his teen year. His belly scales were smooth and not very sturdy, a scrape could cause him some degree of pain. As with most babies, Assasin's horns, and claws were really blunt and not very stab worthy. In his teen years(subsequently the day Kindor was created) Assasin gained pupils, as well as the gradients and his belly-plates became razor sharp. This only fed many dragons' belief that he was cursed being and made life harder for him. As an adult, Assasin has very strong, very sturdy belly-plates, as well as very stab-worthy horns. His eyes narrow as he grows older.
2. Assasin has what's called 'piranha teeth'. As a child, they weren't quite as deadly as later in life, merely looking scarier than they actually were. In his teen years they became absolutely deadly, often used to tear whole chunks out of his victims. His jaw jutted a little further out when he was a teen as well. As an adult, Assasin can practically unhinge his jaw to accommodate the ever-growing 'piranha teeth' which no dragon wants to be on the receiving end of. Assasin's large teeth also retract into the roof of his mouth so unless he's in the biting mood, you won't see them.
3. Assasin's razor-sharp tail blade started out as a blunt piece of metal on the tip of his tail without the armored plates. It was better used as a sort of club then a stabbing instrument. In his teen years it became sharp, but not too sharp, making it incredibly difficult to go through bone, often breaking the metal, which resulted in the agonizing process of regrowing said metal. The metal plates started showing up to reinforce the blade and make it less flimsy. As an adult, Assasin can easily stab his tail blade through an adult dragon's skull, although he doesn't use it that way very often. The metal plates make it nearly impossible to break nowadays, thankfully.

4. Assasin doesn't have his wing claw as a baby. It's a blunt finger, mostly used for balance when trying to fly. His wings are small, and stubby and lack the elbow finger that will grow later in life. In his teen years, Assasin's middle wing finger managed to surpass his index finger, making the wing oddly shaped and forcing him to learn how to fly again. The addition of the elbow finger balanced him out a bit, but ultimately it's used to reinforce the wing when he uses it as as a weapon, hooking the jagged claw on the fleshy finger as a hook. As an adult, Assasin still uses his wing thumb as a hook, with the addition of a metal claw on the tip. His wings went back to a streamlined look, with the elbow finger keeping its relative length.