This is a rather obscure and I believe easily missed detail of the Halo series that has been largely removed since Halo: Reach. I believe that this causes slight imbalance problems and that it should be restored, but this detail seems currently overlooked in the Halo Improvement discussions I often see on these forums.
What is Bleedthrough? It is the carry over of damage from a player’s shield to the player’s health, like when you get sniped or grenaded, as well as when you are melee attacked while low-shields. For example: with bleedthrough if you cause 2% damage to a player with 1% shields, 1% of that damage will damage that player’s health. Without Bleedthrough, you can cause an infinite amount of damage to that player’s 1% shield, and although he will lose his shield, he will take 0% health damage because no Bleedthrough means that excess shield damage does not carry over to health.
The lack of Bleedthrough messes with any damage advantage you may have on an enemy in an encouter. We saw how this screwed up the melee system in Reach, and while that has been resolved in H4, there is one final Bleedthrough barrier: standard hitscan/projectile non-snipe/explosive/melee/shotgun attacks.
The biggest example is of the BR vs DMR/CC headshots in a 1% shield scenerio. In H1,2 and 3, all of these weapons would score that headshot in 1 shot. However, in Reach and H4, a shot is required to pop the shield THEN shoot again for the headshot. This means that the BR wins all of these scenerios, since its 3-shot burst causes 3 individual amounts of damage, but the DMR/CC/SCOPED LR have to fire twice to achieve the same affect. This lack of Bleedthrough puts the single shot rifles at a disadvantage, and is something that I would like to see reversed, like in the original trilogy and MLG Reach.
I advocate for the Reintroduction of Universal Bleedthrough across all weapons for maximum sandbox balance. Then other things can be tweaked along with this.
Thanks for reading!
-SMARTAN 427