Abilities are the only solution here.
Splash damage can be added to weapons fire to do damage in an arbitrary radius around the impact using an weapon modifier ability.
Damage from ship death may be a little trickier. There doesn't appear to be an OnDeath AI Usage condition... just OnlyWhenAboutToDie. I'm not sure when exactly that condition actually fires, when the object is actually dying or simply when it's low on health and presumably will die. Doing damage to an area isn't really the problem here it's getting it to do so when it's appropriate and accurate (actual ship explosion). If OnlyWhenAboutToDie fires only when the AI has a chance to use it and isn't actually dead yet, then in order for this to work you'd have ships exploding themselves before they were actually killed. I suspect this may be the case as I would think AI on an object stops running and executing new commands when it's dead (IE doesn't exist anymore). Maybe someone who has experimented with this condition can give a clearer picture of what it actually does.
In either case, having to do this with abilities means that you would have to use an ability slot (or two, if you want to do both) up to add it. This will be a problem on some ships. Capital ships in particular use up all the standard ability slots. There is a hidden 5th ability slot that works with passive abilities only that can be used but is a bit fidgetty when it comes to Dev mode (giving error pop-ups all the time, even though it works fine) and that would only give you one ability slot, not the two you might need for both types of splash damage.
-dolynick
