"You can also try them later."
If they're successful, then they'll also have another weapon aside from controlling the vines that they had.
They're already accustomed to making a lot of energy shields to store their plant energy inside the vines, so it won't take a long time for them to master launching the spines of Thorn.
Of course, because they weren't linked to Thorn, even though they're also plant users, it would be harder for them to coat the spines of Thorn because it already had the plant energy of Thorn.
Of course, they could also leave it be for a longer time until the plant energy of Thorn in it starts to dissipate.
Then, when it's not that strong, they could also slowly move some of their plant energy inside the spine. Then it would be easier for them to cover the spines and control them as their weapons.
It's a good way, when they wanted to use those weapons for a longer time.
