Worked out · Valheim 1.0.17

Best spears

All Valheim spears ranked by damage at max level, damage per stamina over a full combo and the secondary attack, and the best one you can make in each biome.

Strongest spear
Frostfire SpearSpear
296damage
Most damage per stamina
Frostfire Spear
18.5per stamina
Hardest secondary attack
Frostfire Spear× 1.5 for 18 stamina
444damage
First you can make
Flint Spear38 damage at max level
Meadows

Best spear in each biome

Of the spears you can make by then, the one that kills the biome's hostile creatures in the fewest hits, their weaknesses and resistances applied (every weapon by biome).

Biome	Best spear	Hits	Creatures
Meadows	Flint SpearPierce	5	4
Black Forest	Bronze SpearPierce	47	5
Swamp	Ancient Bark SpearPierce	80	9
Mountains	Fang SpearPierce	34	4
Plains	Fang SpearPierce	70	5
Mistlands	Carapace SpearPierce	61	6
Ashlands	Splitnir the StormingPierce + Lightning	81	9
Deep North	Thunderblood SpearPierce + Lightning	78	9

All 12 ranked

Spear	From	Damage	Per stamina	Secondary	Stamina	Block
Frostfire Spear178 Pierce21 Fire97 Frost	Deep North	296	18.5	444×1.5	16	66
Thunderblood Spear210 Pierce60 Lightning	Deep North	270	16.9	405×1.5	16	66
Nord Spear200 Pierce	Deep North	200	12.5	300×1.5	16	66
Splitnir the Storming153 Pierce10 Lightning	Ashlands	163	10.2	245×1.5	16	57
Splitnir the Primal153 Pierce10 Poison	Ashlands	163	10.2	245×1.5	16	57
Splitnir153 Pierce	Ashlands	153	9.6	230×1.5	16	57
Splitnir the Bleeding153 Pierce	Ashlands	153	9.6	230×1.5	16	57
Carapace Spear133 Pierce	Mistlands	133	8.3	200×1.5	16	48
Fang Spear93 Pierce	Mountains	93	7.8	140×1.5	12	30
Ancient Bark Spear73 Pierce	Swamp	73	7.3	110×1.5	10	21
Bronze Spear53 Pierce	Black Forest	53	6.6	80×1.5	8	12
Flint Spear38 Pierce	Meadows	38	6.3	57×1.5	6	4

Formula

Damage at max level = base + per level × (max level − 1), each damage type apart; chop and pickaxe left out of the rating (almost every creature ignores them).

Full combo = (combo hits − 1) × hit + hit × the last swing's multiplier; per stamina = combo damage ÷ (stamina × combo hits). Secondary attack = hit × its multiplier.

Stamina and eitr per attack are at skill 0; skill 100 takes a third off (× 0.67) for every weapon alike, so the order doesn't change.

ItemData.GetDamage, Attack.DoMeleeAttack / FireProjectileBurst, Attack.GetAttackStamina, HitData.ApplyResistance in the code of Valheim 1.0.17.

Assumptions

Skill 50 in the weapon's skill, weapons at their max normal level, no stars on the creatures (a star doubles health, two stars triple it).
Every hit lands and only the primary attack is used; no backstab, no stagger bonus, no armor set or mead bonuses.
Area hits (staffs, sledges, atgeirs) are counted against one creature at a time.
Bows and crossbows fire the best arrow or bolt for the target you can make by then, at full draw.