The error doesn't look like one coming from Weld. As far as I can tell, we do not try to parse faces-config at all.
However, first thing coming to mind is that you use old app with very ancient JSF version, yet you are trying to run that on newer Tomcat and latest CDI version (Weld 3.x implements CDI 2.0 which is Java EE 8).
It might be worth a shot trying to nail down what actual version of various EE APIs are being used. Also, Weld 3 has some integration with JSF that I am not sure was even there when JSF 1.1 was a thing; while this isn't what's causing you any troubles at the moment, it could in the future. I'd first look into aligning the versions you are using.