Actually, for self-defense Arrows are pretty great.
The standard munitions can be used as any artillery against ASFs and ground troops closing in.
With Air Defense Arrows, they are great AA.
As for capital missiles, if you want the option of artillery support without sacrificing capability when closing in (those things are heavy), I recommend the crown jewel of subcapital weapons: The Piranha.
Add one in the nose, it's ammunition isn't too heavy to carry on a dropship, they can server as makeshift artillery, and they are great against attacking fighters in space.
Though then it's obviously not succession wars anymore - but neither are non-tele-operated capital missiles.
For Trutzburg-Style planet hops for direct artillery support, Long Toms are better, but you definitely lack armour for that.