GetWeaponEnchantInfo();

This appears to be used for handling TEMPORARY enchants to weapons - like POISONS. Also appears to be self-only.

Returns

hasMainHandEnchant, mainHandExpiration, mainHandCharges, hasOffHandEnchant, offHandExpiration, offHandCharges, hasThrownEnchant, thrownExpiration, thrownCharges

hasMainHandEnchant = 1 (true) or nil
mainHandExpiration = time remaining as thousandths of seconds
mainHandCharges = charges remaining
hasOffHandEnchant = 1 (true) or nil
offHandExpiration = time remaining as thousandths of seconds
offHandCharges = charges remaining
hasThrownEnchant = 1 (true) or nil (new in 4.0.1)
thrownExpiration = time remaining as thousandths of seconds (new in 4.0.1)
thrownCharges = charges remaining (new in 4.0.1)

Reference the default interface BuffFrame.Lua for its usage.