Go into the data editor and find the zealot's weapon, than look at what it says for 'Effect - Effect'. Find that effect and change the damage type from melee to splash, than change the 'Search - Area+ ' field how you want it. Arc specifies where relative to the unit the enemy must be in order to take damage. For example 360 is a full circle around the unit, and 180 would be anything that is in front of the unit. Someone can probably explain that better than me... but I think you get the idea. The rest of the fields are pretty self explanatory I think.
How to change the radius of splash damage for zealot for example.
@TreantBG: Go
Go into the data editor and find the zealot's weapon, than look at what it says for 'Effect - Effect'. Find that effect and change the damage type from melee to splash, than change the 'Search - Area+ ' field how you want it. Arc specifies where relative to the unit the enemy must be in order to take damage. For example 360 is a full circle around the unit, and 180 would be anything that is in front of the unit. Someone can probably explain that better than me... but I think you get the idea. The rest of the fields are pretty self explanatory I think.
10x it works :)