Arquillian.xml

<property name="browserCapabilities">${browser}</property>

You can use Maven filtering of the test resources like this:

Pom.xml

        <profile>
            <id>browser-firefox</id>
            <activation>
                <property>
                    <name>browser</name>
                    <value>firefox</value>
                </property>
            </activation>
            <properties>
                <browser>firefox</browser>
            </properties>
        </profile>

...

    <build>
        <testResources>
            <testResource>
                <directory>src/test/resources</directory>
                <filtering>true</filtering>
            </testResource>
        </testResources>

Or you can setup surefire execution to set system properties:

                                <configuration>
                                    <systemPropertyVariables>
                                        <browser>${browser}</browser>
                                    </systemPropertyVariables>
                                </configuration>

Non of the options works perfect from IDE, tho the filtering probably works better then the pure surefire version.

If you have any bright ideas, we're discussing the future of the configuration here: https://community.jboss.org/message/777830