Combat Skills

Weekend - 10% boost to /k during the weekend
Dwarven Warhammer - 40% boost to /k outside the wilderness
Dwarven Blessing - 20% boost to /k
Amulet of Zealots - adds 5% boost to Dwarven Blessing. Additional 5% boost for /k in the wilderness
Gorajan - 10% boost to /k for having the appropriate full set of gorajan equipped.
Attack Master cape - 15% boost to /k when training melee (ranged and magic master capes will add 15% boost when training their respective skills)
Infernal Slayer Helmet - 18% boost to slayer tasks
Infernal Slayer Helmet (i) - 22% boost to slayer tasks
Rocktails - 7% boost to /k when food is consumed
Hellfire Bow - 3x boost to /k in wilderness
Void Staff - 8% boost when training magic, uses 5 elder runes per charge.
Superior Dwarf Multicannon - 37%-65% boost when using a cannon

Full Gorajan and a combat master cape for the respective skill you are training

The best xp rates for these skills are obtained through killing Vet'ion with the maximum possible boosts; those being the following: