Here is a vision of how to instill a full Arena purity in Halo X1.
Loadouts: Loadouts should be stripped down to: Assault Rifles, one selectable grenade, one munition perk, one character perk, Armor Abilities (rebalanced), Sprint default
Assault Rifle options: standard assault rifle, smg, saw, Brute spiker, Brute plasma rifle, Storm rifle, suppressor, and two new forerunner/promethean assault rifles (assume that all rifles are balanced with some having high fire rates low accuracy/distance or the reverse slow fire rates higher accuracy/distance). * Covenant Plasma weapons would now be re-loadable from dropped weapons, except when charging a plasma burst*
Grenade options: all grenades from Halo are selectable but max carry amount per type is two and can carry only 2 different types of grenades at any time
Munition perks: Munition perks should be: Ammo Clip+, Grenade explosion radius+(lower damage), Grenade lobber (farther grenade throws), Grenade bouncer (grenades ricochet of ground and walls with more movement), and other mild enhancements to standard ammo and grenades possible
Character perks: Shield regeneration boost (mild speed boost 10% to 15% faster), Jump booster (jumping height increased about 1 foot), Sprint endurance (sprint 10% to 15% farther/longer), Radar extender, and other mild character boosting perks
Armor Abilities: Armor Abilities should have a use based depletion/regeneration system, all AAs would have 15 seconds of use so that if you use 3 seconds then only twelve seconds would remain and once a full depletion has occurred the it would take 1 minuted and 15 second to regenerate the AA. I would think under this system all AAs could be viable.
Sprint: Sprint would return but be slightly slower and last a shorter distance
Ordinance Drops: Ordinance Drops should be only primary weapons, secondary weapons, and grenades. Also Ordinance Drops would be given only on player command and no perk for them to drop otherwise.
Spawns: all spawns are 10 second countdowns unless suicides or betrayals
Sketchy Possible Ideas: Sprinting slide (ripoff CoD Ghosts), Sprinting parkour (for crossing small gaps or clearing small obstacles)