For web.xml, do you mean the global one, or the one in your WAR? For the global one, I am not sure but I think that the changes will be picked up when a WAR is deployed/redeployed, and then only for that WAR.
For loginc-config.xml, you need to restart the app server.
For login-config.xml, you may invoke stop/start method in jmx-console - jboss.security - service=XMLLoginConfig
To hot deploy the applications web.xml you only need to update the EAR file.
In case of exploded deployment you need to touch META-INF/application.xml, only this file is monitored because of performance.