A problem with Reap Spirit pet builds is that you cannot assign a devotion proc to the spirits themselves. A nice solution would be an different options for the skill itself and the summoned spirit. For example when you open the skill menu to choose an ability to assign, you would have an two options for Reap Spirit: Reap Spirit (skill) and Reap Spirit (summon).
Obviously you cannot have the summon variant as an option for all devotions. For example Shephard’s call would only have the skill variant available to choose from.