<p>I was reading this post on pike AI for NPCs, but I'm not very optimistic about it due to Minecraft AI limitations. As I said there, suggestions regarding 'better AI' and complicated combat mechanics are discouraged, but a weight mechanic may be a good alternative approach.
</p><p>Weight would be a speed and jump modifier determined by armor and in-hand item (typically weapon). Wearing heavier armor sets and holding a heavy or unwieldy weapon, like a pike, could slow down the player.
</p><p>This change is not intended to make the game 'more realistic' for the sake of it. Hell, I don't think out-of-hand inventory slots should affect weight at all (major Minecraft plot hole). It's purely based on the need to balance combat, both pvp and npc, from being dominated by heavy, long-range weapons.
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(Edited by Adonnen)