Holy Symbol: Tricorder or Sonic Screwdriver type portable device. It's not that the device is that rare, or expensive - you need specialized training to use it though. Other characters cannot pickup the device and make use of spell effects.
The device would have 120 points per 1st level spell representing an upgraded device and/or more efficient usage as the Man of Science increases in level and ability. Since it wouldn't make sense to have them only be able to use one "spell" per day and have it used up all at once we can break all the durations into 1 minute (round) lengths and allow the player to subtract their usage from the total.
Energy used:
Cure 20 points per hp restored
Detect 2 points per minute detecting "life"
6 points per minute detecting "magic"
Light 1 point per minute
Warding 1 point per minute
(Remove) Fear 120 (full energy slot)
Resist Cold 2
If you changed Evil/Undead to Mechanical/Robots the Cleric's turning ability would make sense in the context of using the tech device to affect their circuitry.
Higher level spells would include scans to locate objects, medicine to cure diseases, research to get answers, and even advanced science to raise the dead back to life!
This might be suitable for a Weird Fantasy/Science type game where you wanted to leave matters of faith more ambiguous, or want all "magic" to operate in the same way via the Mage's spell list.
