If you are lover of privacy like I am, you'll love this configuration.
Firstly, you need to start tor.
sudo systemctl start tor
Then add proxy with this command
/proxy add tor socks5 127.0.0.1 9050
If you want to setup when you connect to any irc server to use proxy, execute this command
/set irc.server_default.proxy "tor"
But, if you want for specific server run this
/set irc.server.server_name.proxy "tor"
Of course you should change server_name with server name.
Tor and ssl_verify don't like each other so you must turn ssl_verify off.
/set irc.server.server_name.ssl_verify off
You can also set this for every irc server, but I don't recommend it.
/set irc.server_default.ssl_verify off
If you want to enhance your privacy run this commands.
/set irc.server_default.msg_part ""
/set irc.server_default.msg_quit ""
/set irc.ctcp.clientinfo ""
/set irc.ctcp.finger ""
/set irc.ctcp.source ""
/set irc.ctcp.time ""
/set irc.ctcp.userinfo ""
/set irc.ctcp.version ""
/set irc.ctcp.ping ""
/plugin unload xfer
/set weechat.plugin.autoload "*,!xfer"
After all this you just need to run one more command
/save
And that's it, you have irc tor proxy.