A fast blow at 30 fps jumps 30–65 cm between two frames. A trigger collider on the weapon only looks where the weapon is on each frame, so it misses most of what the blow passes through. HitForge reads your attack animations in Blender, finds the frames where each blow is live, builds the weapon and fist capsules and the hurtboxes, and gives Unity a sweep that follows the blow between frames. Then it measures what each way of checking would miss, in Blender and again in Unity.

What you get

• Active frames found for you: from the speed of the weapon or fist in every action. The wind-up and a mocap clip's jump to its first pose are not taken for blows. To set a window yourself, move the hit_on / hit_off markers it writes into the action; markers win over the speed rule.
• Strikers: a weapon parented to the hand bone, or a fist, foot or knee. A body part is fitted to its skin as posed during the blows, so a clenched fist does not get the open hand of the rest pose. Each striker becomes 1–4 capsules that hold all of its surface, faces as well as vertices; a fist is then checked half way between the frames it was fitted on.
• Hurtboxes: colliders on the bones, fitted to the skin and then checked on the moving skin through all your animations.
• Unity: the setup writes HitForgeOn / HitForgeOff events into the model's clips (your own events stay) and places strikers and hurtboxes on the bones, whatever your FBX axis settings. At runtime each target is hit once per blow, the character's own hurtboxes are never hit, and an attack interrupted before its last frame switches its striker off. The striker checks the whole way it travelled since the last frame, along the curve through its last three frames, not a straight line.
• Proof in the engine: Check poses each striker with Unity's own clip and measures, in mm, how far it lands from Blender's. Measure replays every blow at 30 and 60 fps with Unity's physics and counts the targets a trigger collider misses and the targets HitForge misses.

Measured

• UE5 mannequin, two attacks, fist and crowbar, in Unity 6: at 30 fps a trigger collider misses up to 62% of the targets the blow touches, HitForge 0.75%. At 60 fps: 28.1% and 0%.
• CMU motion capture, six blows with a bar: the trigger misses 8–15% at 30 fps, HitForge 0.08% at most.
• A straight-line sweep between frames, the usual fix, still misses up to 4.3% at 30 fps; the curve through three frames misses 1.3% on the same blows.
• Strikers posed by Unity's clips land within 7.3 mm of Blender's with Unity's default animation compression, and within 0.0 mm with it off.
• Fitted as weapons on all 45 props of a CC0 library without a failure; the panel shows how much air the capsules add around each.

Blender 4.2 to 5.2, tested in Unity 6. Works with rigs that have no mesh (mocap with a weapon). No AI, no cloud, no account.