When a power says STR vs AC, it means it's an attack modified by STR, not that just you just add your STR mod to the roll. Also, you aren't including the proficiency bonus to attacks with your weapon.
Your level 17 Symbol of Life provides a +4 bonus to cleric powers with the implement keyword.
So Jack should have ( I think)
basic sword attack: +21 (+6 STR, +8 level, +4 magic, +3 prof): d10+12 (+6 STR, +4 magic, +2 weapon focus)
basic crossbow attack: +12 (+1 Dex, +8 level, +1 magic, +2 prof): d8+2 (+1 Dex, +1 magic)
Lance of Faith: +17 (+8 level, +5 WIS +4 magic): d8+11 (+5 WIS +4 magic, +2 Astral Fire)
Righteous Brand: +21, d10+12
Sacred Flame: +17, d6+11
Encounter:
*** (Prophecy of Doom)
Awe Strike (+21 vs. Will): 1d10+12
Mantle of Glory (+17 vs. Will): 2d10+11
Sentinel Strike (+21 vs. AC): 3d10+12
Daily:
Avenging Flame (+21 vs. AC): 2d10+12
Divine Power (+21 vs. Fortitude): 2d10+12 (Astral Fire doesn't stack with weapon focus here)
Purifying Fire (+17 vs. Reflex): 3d10+11
***: I don't think you can trade out the powers you get from your paragon path, so you'd have to have Prophecy of Doom. I dropped the lowest level encounter power you have to make room. However, you might want Daunting Light instead of one of the others since it's a ranged attack.
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Healing Word upgrades to 3 shots per encounter at level 16.
Shields of Protection are a STANDARD action to use, unlike most of the other items.