Chains Again!
The sky was quickly mending the shattered space whenever the black dragon passes through it, as the space of the entire world wasn't something that could be destroyed that easily, but cracking it is always achievable.
The black dragon was more like a baby in size if he is compared to the Divine Phoenix, but even with that superficial mental boost, the duo up in space weren't feeling the least confident in taking him down with one attack.
Some people might misunderstand that as cowardice or lack of courage and confidence, but regardless of these thoughts that seemed to be true, they frankly aren't the bit on point.
Moreover, it's something that goes way deeper than that and contains a lot more depth that is yet to be found inside of it.
After all, these two weren't the bit afraid, they were more like realistic with their train of thought.