@Vaellian something that is a fun melee ability that works well with a caster centric build is actually the ERE "Sunder Soul" that converts Sunder Armor into an 80% weapon dmg Shadow attack that costs 15 rage and generates a Soul Shard on kill. This can also be combined with the ERE "Shadow Strikes" which makes melee abilities be able to trigger the "Nightfall" talent in Affliction Warlock tree.
This means you can have instant cast Shadowbolts proc'd from your melee spam for a fun hybrid, enjoy ^ ^