Arch is a minimalistic linux distribution, so normally there are no other special configuration files which are getting included in some strange placces, modified by system configuration wizards.
`/etc/profile` is the right place to do this for a system wide configuration.
> This file is intended to be used for ALL common Bourne-compatible shells. Shell specifics should be handled in /etc/profile.$SHELL where $SHELL is the name of the binary being run (discounting symlinks)
It is also mentioned in the official FAQ for reloading if your shell can't find a newly installed binary