My advice would be to put these resources in their own separate jar module and then have the war use them as a dependency. That way the war and any other project could refer to the resources as if it was any other dependency.
But if you don't want to do that or you can't, I think you'll have to use a classifier. As I said, this isn't ideal. Here's a detailed tutorial on how to do it:
<build>
<plugins>
<plugin>
<artifactId>maven-jar-plugin</artifactId>
<executions>
<execution>
<id>only-library</id>
<goals><goal>jar</goal></goals>
<phase>package</phase>
<configuration>
<classifier>only-library</classifier>
<excludes>
<exclude>**/Main*</exclude>
</excludes>
</configuration>
</execution>
<execution>
<id>everything</id>
<goals><goal>jar</goal></goals>
<phase>package</phase>
<configuration>
<classifier>everything</classifier>
<includes>
<include>**/*</include>
</includes>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>