I've looked around and it is hard to find up-to-date information on what the Phantom actually shares with the caster or has by default.
I can't see how abilities, talents, or basic bonuses from equipment are related, if at all. Its attack looks like the lightning portion of Kalakoth's Minor Blights in the log, but with more accuracy than my caster. Doesn't seem to have a Blast effect so far. The Phantom's Deflection is higher than my caster and its DR against Slashing, at least, is lower. Its attacks seemed marginally slower.
Items with Spellbinding no longer seem to work, including rings.
Items with Spell Holding do appear to work - my Phantom was activating Consecrated Ground and Holy Meditation all by himself.
Does anyone know more specifics about this spell and/or Substantial Phantom?