Spiritual warriors are fairly easy to kill. They have very high defence and health for their level, and will rarely hit over 100. They do however use only melee attacks, which may either be slashing or crushing depending on the warrior. Here are several areas to kill them and what you should do if you kill them there:
The main room only contains Saradomin spiritual warriors. As most Zamorakian minions are at the northern part of the main area, it would be best to kill them there. Most of the warriors are busy fighting, and it is uncommon to find idle warriors around. This does save food resources, but Saradomin, Armadyl and Zamorakian protection would be recommended.
This area contains numerous spawns of Spiritual Warriors. However, players should take notice of the prayer drain, and always drink a sip once you get inside. The best place to kill them is right outside the boss room, as many Spiritual warriors are wandering around. You should be aware of the Spiritual mages as higher levels may misclick and be unable to damage them. This is, however, one of the best areas to slay Spiritual warriors when a player is on a task.
This area of godwars has several Spiritual warriors, most of which will be fighting the Zamorakian monsters in the encampment. This makes it slightly easier for lower levels on slayer tasks. These Spiritual warriors lie near the entrance to the encampment, as well as outside of Commander Zilyana's room.
This area contains Spiritual warriors with high defence against melee and ranged attacks. Free prayer recharges can be found in almost every world due to the popularity of their general. These warriors barely fight any Zamorakian, aside from the occasional vampyres, so unless you can camp them carefully, it is not recommended to kill them.
The spiritual warriors here can only be hit with range, magic or salamander attacks. These warriors are few in number. Unless using magic, it is not recommended to kill them here due to the fact that ranging them takes a long time as warriors, they are strong against rangers.
Spiritual warriors originally dropped level 2 clue scrolls, but were updated to drop level 3.
Although the Saradomin Spiritual warriors wield swords, they seem to be attacking their enemies by punching them, rather than hitting them with the sword. When defending from an attack, they also defend as if they had no hand equipment, despite the kiteshield.
Same as above, when attacking a Zamorakian Spiritual warrior, they have an anger mace and kiteshield just like their Saradomin versions. However, attacking them will cause them to protect themselves with the animation if they had no weapons/offhand on them and attack via punching.
For a while, Zamorakian Spiritual Warriors used magic attacks instead of melee. This has been fixed.
Before the Evolution of Combat, Armadyl's Spiritual Warriors used ranged instead of melee.