Ozul didn't tell them about his strength.
If Kure knew that Ozul was now strong enough to completely dominate the fight even if all three of the remaining Rank-10 Mages joined hands against him, he wouldn't have been in such a hurry to visit the site of Darcia's death.
Instead, he would have been racking his brain to think up all the ways he could make Ozul join the family.
If Ozul backed the Ashin family, then they would undoubtedly become the number one rulers of the entire Mainland!
Unfortunately, even if Kure did know about Ozul's strength, he wouldn't have been able to tie him to the Ashin family.
Although Raymond and Alver were a little surprised at their father's sudden burst of energy, they quickly recovered since they also understood the importance of such an artifact. If they got their hands on it, it wouldn't be difficult to take over the Leonard Dynasty if it ever caused any troubles for the Ashin family in the future.
"HAHAHA!!"
Really sorry for no update last week...