I've been finding something that does this and can't find any. So I created it myself.
This module is for ROMs that doesn't have headset icon. Don't use this on ROMs that already has one. Example: RR, TouchWiz, LG, etc.
If anyone has any issue please create one on GitHub repo and attach logs.
Free download: Xposed Module Repository
Buy it on Google Play™ if you want to support the dev.
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Headset Icon, Xposed for all devices (see above for details)
Source Code: https://github.com/paphonbth/CMHeadsetIcon
Xposed Package Name:
Current Stable Version: 1.1.1
Stable Release Date: 2016-06-20
Current Beta Version: 1.0.2
Beta Release Date: 2016-06-19
Last Updated 2016-07-25