In my world, there is a tribe that covers themselves in ash and attacks in the dark, with torch spears. While this is clearly a really good way to be seen and picked off by archers, in a time of superstition and belief in spirits would this be a good tactic to frighten their enemies?
I think the benefits don't weigh up against the downsides.
An additional downside to take into consideration is that the spears will negatively affect the vision of the warriors. Having a bright source of light in front of them instead of behind them, will blind them and wash away the darker visuals in front of them.
So they will see less, while they become better visible to their opponents. You can easily try this out at night on a walk or such.
It depends on a few factors:
- Is the tribe known for wielding flaming spears into battle? Are they known for beating their enemies? The enemy's perception would be such if the tribe has a long history of warfare and a tradition of carrying burning spears into battle. So this would be arousing fear on account of reputation.
- Is the tribe completely obscure and uses this method unlike any other tribe or clan etc. This would arouse fear on account of obscurity. People fear the unknown.
- Does the tribe use powder/resin/oil mixtures to color the flames and make them look really otherworldly? This causes fear on account of superstition alone, especially if no one else knows these techniques.
If the answer is 'yes' to the above questions, the same answer goes for your question.
Covering themselves in ash and attacking at night also gives a ghostly appearance, I would presume, so the scare factor rises again. If the samurai were able to use a fairly banal thing like a stylized facial armor (Mempo) to scare their enemies, a famous/obscure ash-covered warrior tribe wielding strange-colored flames in the night would definitely spark fear in any enemy.
I'm going to assume that by hunter gatherer society they don't do much metalworking. This means that their spear is going to be made of mostly wood, bone, sinew, and rock. A flaming spear made of such materials is going to be structurally weakened and unbalanced by the attachment of a wick.
Sure it would look scary at first, but attacking like this loses the element of surprise. There aren't any lighters or matches available so a small fire would need to be built to light the torches. This could be done out of sight of the enemy meaning that they would be detected as they approach, or a fire could be built immediately before the attack which would attract curious people wondering "Why does our enemy stop to build a fire before attacking us?".