It's just very formal and old-fashioned, maybe even archaic:
tr.v. pur·posed, pur·pos·ing, pur·pos·es
To intend or resolve to perform or accomplishhttp://dictionary.reference.com/search?r=67&q...
Oxford Dict of Eng
purpose (with object) (formal):
have as one's intention or objective: God has allowed suffering, even purposed it
Most of the examples I found of "purposed" are from the Bible or probable mis-spellings of "proposed". But here are a couple:
"It appears from a document found in his possession, he purposed leaving this
country for the Continent" http://www.stedmundsbury.gov.uk/sebc/visit/ar...
"so shall it come to pass; and as I have purposed, so shall it be." "The Lord
of hosts hath purposed, and who shall disannul it? " http://www.strictlygenteel.co.uk/plan/chapter...