The AR9271 does not need non-free firmware to work on OpenBSD, and also in LibertyBSD.
You just need to use a port to install it, or, if you prefer, just download the athn-firmware, which is in the package repositories of LibertyBSD.
Just remember this:
1) You need to "export" the repository. So, you can run this command (root mode): export PKG_PATH=http://libertybsd.net/pub/LibertyBSD/5.9/packages/$(uname -m), or modify the root's .profile file to don't need to do it every time you want to install something, like this:
Be sure you are not in /home/youruser/ directory, you should be here: /root/.
Maybe you don't have nano installed to make the file's modification step, so first:
# export PKG_PATH=http://libertybsd.net/pub/LibertyBSD/5.9/packages/$(uname -m)
# pkg_add nano
When you get it, just do the root's .profile modification, like this:
# cd /root/
# nano .profile
Make an "Enter" space between the first tree commented lines and the first non commented line, and immediately upside the first non commented line, put this: export PKG_PATH=http://libertybsd.net/pub/LibertyBSD/5.9/packages/$(uname -m)
Then Ctrl+X > Y > "Enter"
2) Now you can install the athn-firmware package.
# pkg_add athn-firmware
Well, the question here is: Do you know how to use Wi-Fi in OpenBSD/LibertyBSD?
Because you use the athn-firmware, it should be like this:
To scan the Wi-Fi signals around you.
# ifconfig athn0 scan
To connect (if the signal uses other encryption, like wep, just change the wpakey for nwkey).
# ifconfig athn0 nwid YOUR-WI-FI wpakey YOUR-PASSWORD
# dhclient athn0
It will connect!