Instead of having to rely on a separate tool, the use of (custom) Yara signatures from within SEP would offer a significant possibility and capability to react quickly to emerging threats.
In some cases, SEP content is not sufficient to detect some of those threats. Or a threat is so specific that Symantec cannot, for some reason, react to certain threats.
Capabilities using Yara signatures from within SEP could potentially bring a greater, better, faster detection. And in doing this will make te SEP product a lot more effective.