I am comparing between those versions because I'm currently working to upgrade weld in my web application, from version 1.1.24 to 3.1.0. I know that a lot of changes have been introduced between those versions, but I commented this just because having the same project configuration, this could look like a regression regarding Tomcat startup functionallity using Eclipse.

Regarding how the deployment is made, I make use of the Eclipse server option "Serve modules without publishing"[1], this way I'm serving the application directly from my workspace.

For the moment the best solution I have been able to achieve is to deploy the beans.xml in WebContent/WEB_INF/beans.xml inside my sources path. With this configuration:

1) I'm able to start Tomcat 8 (or higher) in Eclipse in all the cases
2) I'm able to start Tomcat 7 in Eclipse without making use of the "Serve modules without publishing" option
3) Tomcat 7 does not start in Eclipse if I make use of the "Serve modules without publishing" option

[1] https://stackoverflow.com/a/16385765/8579169