David knew it was a risky plan just to send Nasiah off. However, this was a calculated endeavor first to get rid of the orcs without using much manpower or to have to use his own strength and possibly endanger others.
It was also good to get Nasiah's name out in the wild so that others would know more about him. A way to spread a reputation for the whole family.
He also read up on Elyia, knew her personality well, and guessed how well it could clash with Nasiah to teach him a few things about the world that would be better through experience rather than just simply telling him.
The biggest risk in this endeavor was the power of the orc Warlord. Depending on how powerful they were, it could end up with disastrous effects on the landscape and on Nasiah himself.
If they did ascend to such a powerful state of existence as that they could develop an Elohim Core, then that would pose a significant issue to how Nasiah could handle it.