LOL, its late here and I've been up for nearly 48 hours with an ill dog so if I'm barking ;-) up the wrong tree please make allowances.
Have a look at this quote from wiki concerning the green man in other cultures:
In his A Little Book of The Green Man, as well as his website, Mike Harding gives examples of similar figures in Borneo, Nepal, and India: the earliest is a foliate head from an 8th century Jain temple in Rajasthan.[13] He also notes that heads from Lebanon and Iraq can be dated to the 2nd century and that there are early Romanesque foliate heads in 11th century Templar churches in Jerusalem. He tentatively suggests that the symbol may have originated in Asia Minor and been brought to Europe by travelling stonecarvers.
Other gods depicted green are (in Tibet) Amogha-siddhi and (in Mexico) Tlaloc.
In Sanskrit the Green Man is cognate with the gana Kirtimukha or "Face of Glory" which is related to a lila of Shiva and Rahu. The Face of Glory is often seen in Vajrayana Buddhist Thanka art and iconography where it is often incorporated as a cloudform simulacrum; and depicted crowning the 'Wheel of Becoming' or the Bhavachakra.[14]
If you want to see his site:
http://www.mikeharding.co.uk/
Chesk out the green man section and 'green man in India'. Some similarities.
He says: ' If we suppose a common Indo-European origin for our language then the idea of symbols and myths travelling across to Europe from India and Persia seems less than fanciful to me'
Obviously its a more distintly 'Indian' image in the above pic, but the fact that it IS more like a European 'green man' image and not a 'face of glory' Indian/asian image is very interesting. Yours looks very much more European, in fact the entire piece looks like that oriental influeneced european carved Ivory from the medieval period onwards.
The V&A has a similar dagger to yours but I cant find a better picture:
