It's worth noting that Zodiark was a necessity to resolve the damage inflicted by the Final Days. Without the first and second round of sacrifices then there would not even be an Etheirys to speak of. In addition to that, the Final Days only happened because Venat chose to not mention their approach only to then whine when...her people decided to work to fix the problem.

I wouldn't consider doing everything possible to preserve one's species and loved ones to be 'weakness'. If anything, it's a commendable and understandable goal. Especially when the tragedy inflicted upon the Ancients was entirely avoidable and almost exclusively due to Venat's initial inaction and then her bizarre decisions in the aftermath.