You know, if I had my way...
Combatant's cape would have the highest combat stats in the game, work as avas, work on ice strykewyrms, AND provide a +6 boost to ASDRMHP that stays as long as you wear the cape
Artisan's cape would act as cooking gauntlets, 5% chance to make a free potion of any kind when making potions, 5% more powerful bonfire boost, 5% chance to make extra stuff when fletching, crafting and smithing materials require 1 less item (bar, hide), and gives you a 100% chance to make combo runes, and you make 2x combo runes. Gives free teleports to cooking guild, blast furnace, runespan, crafting guild.
Gather's cape will act as a full camo outfit, would incite implings to fly to you when you are in range (say, a render distance), causes all crops to skip the first state of growth when you plant them, gathering div chronicles gives you 500 energy when you capture them, when worn, gives you a 50% chance not to use up your cap on divine locations, boosts rate of gathering for mining, fishing, wc by 20%, and makes the resource node last longer, causes mobs in LRC to ignore you
Gives free teles to any divination spot, mining guild, fishing guild, LRC, allotment patches, and each of the main hunting areas
Support cape would have all the theiving based boosts from the ardy cape (even if you don't have it), would allow you to pick between two slayer tasks (3 with ticket), twice a day, allows you to regen hp at 5x rate while running, never fail an agility obstacle, and you can take this cape into daemonheim.
All capes, sans combatants, will have the stats of regular skillcapes. Combattants cape will have 200 health, 62 armor, 6 prayer and 31 damage