kronckew i have a taiaha similar to yours , i also believe it is 20th century ( i cant say early mid or late)
Everything i have seen posted here to me looks mid to late 20th century or even newer...
A good resource is the tepapa museum archive located here :
for taiaha:
http://collections.tepapa.govt.nz/se...iaha&scope=all
for mere:
http://collections.tepapa.govt.nz/se...magesOnly=true
Another recent mere i esquired about can be found here
http://www.liveauctioneers.com/item/...b-patu-pounamu
This one to me actually doesn't look that bad, but its definitely a tourist or recent made piece, the size gives most of them away... oh and ignore the possible 19th century ... its not but the price was ok in my opinion.
I've included some pictures of my taiaha (156 cm)