TLDR: Give the Zealot more powergrid, a drone bay and either range or a mid in order to make it a competitive fleet ship or small gang ship.
Problem: The Zealot is extremely weak right now. It lacks the powergrid for both a decent tank and decent guns. It lacks the mids and dronebay to be a truly good small gang ship. In fleets, because it’s armor, it’s slower than most competitors. Because it has beams, it’s at a range disadvantage as well. The lack of a drone bay and dedication of lows to tank generally gives it a DPS disadvantage, and finally, anything that a Zealot can do, a Legion can do better at ~100 mil less.
More powergrid. At all level 5, it should sit in the 1700-1750 PG range without additional modules (compared to the 1475 PG it has right now). This would allow it to fit an AB, a meta 1600mm plate and T2 Heavy Beams, while forcing meaningful sacrifices in order to add additional tank or fit an MWD.
Give it a drone bay. Probably 25 bandwidth, 50 bay. This would give it up to about an extra 100 DPS, making it somewhat competitive in the DPS department while keeping with the Amarr flavor of having some drone flexibility with 2 flights of lights (compared with ships like the Eagle, Muninn or Deimos).
Option 1: Get rid of the activation cost bonus and replace it with a 5-7.5% optimal range bonus. This would extend its practical range to just under that of Caldari HACs, and would separate its role from that of the Legion.
Option 2: Get rid of the activation cost bonus, replace it with a resist bonus, and trade a lowslot for a midslot. This would give it viability as a brawler/small gang ship, much like a Deimos.