HelenaSophiaSucgang thank you for suggesting this theory. They were the one who brought this to my attention since I forgot.

Small spoilers 

It's come to my attention that Toshiro has been able to use his ice powers since before he even had a zangpakutō. He's never really needed a sword in order to freeze things. The evidence of this is very strong. Such as when he was a child. The evidence was clear as day then.

During one of the episodes, we see small parts of Toshiro's past, and when he met Rangiku. When he was having one of his dreams again, he ended up freezing the entire room. This was before he even had a zangpakutō or knew Hyorinmaru's name. 

In "Diamond Dust Rebellion", when Toshiro stops hiding his Reishi, it started snowing. It meant he lost control over it. Toshiro can affect the weather without even drawing his sword. It suggests that he has to hide his reishi all the time otherwise he will lose what control over it that he has. It wouldn't bode well for the Soul Society, seeing as Toshiro is one of the strongest people there who can't completely control his power.

Now if you look at the Thousand Year Blood War arc of the manga, in chapter 671, he becomes an adult. I'm not sure if this is an error, but you don't see his zangpakutō much after he became an adult. Either he doesn't need to use it, or he fused with it. I'm not sure. But he's able to use his abilities to a much larger extent. Flash freezing everything in front of him if he chooses to. You can't even touch him without being frozen. It makes him almost if not more dangerous than Ichigo when he's angry. All Toshiro would have to do is slightly move his hand and Ichigo is basically done for. 

It shows that simple hand movements are all that Toshiro needs as an adult whether he has his zangpakutō or not, he can use his power no matter what. So people better hope that when he does get to that age that he can control it more than he can now. 

Toshiro belongs to Tite Kubo