Weapons that deal damage in later rounds

Question

I am DM'ing a D&D 3.5 campaign and a player asked me an interesting question.

I love toying with homebrews and out of the box ideas so figured I would post this and see what people thought.

The player was wondering if there is a weapon that deals no damage up front when it hits, but increased damage on a later round (so for instance instead of a d6 the round the attack occurs it would deal a d8 the next round or some such thing). The only thing I could think of similar to this would be poisons, but poisons deal primarily with ability damage and the player is looking for regular damage. Not sure how feasible this is or what it would even be useful for, or that I even agree with the concept so figured I would fling it to the internet and see what sharks were biting,

Answer 1

The harpoon is an exotic thrown weapon detailed in Frostburn. It does deal damage upfront, but it also gets lodged in an enemy, which inhibits their actions until they dislodge it (a full-round action) at which point it deals its damage again. On top of that, you can attach a rope to a harpoon, so that you can (try to) limit their motion even more. All in all, these make the harpoon a rather good weapon—but for its controlling properties, not its damage. Getting to deal damage a second time off of one attack is nice, but the full-round action they burned doing it is the far more serious thing it did to them.

To my knowledge, this is the only notable case of delayed weapon damage in 3.5. Pathfinder, which is a spin-off of 3.5, included somewhat more, particularly standardized bleed damage that weapons could deal (but this is more regular hit + slow damage over time, rather than no initial hit + big damage after a delay).

Answer 2

If the pathfinder elements included alchemists and bombs, then a homebrewed bomb variant with a slightly delayed detonation and an adhesive could at least provide damage on the second round.

Outside of that, a specifically-researched enchantment or spell could conceivably confer that effect to a weapon.

Answer 3

Alchemists Fire on a hit does 1d6, then 1d6 on the remaining round. No reason you couldn't have either bolts of alchemist fire, or say, springloaded bolts that expand inside the enemy on the next round.