If you are truly worried about Constitution, and don't mind starting with mechanics and building from there, you can start with pre-racial Dex 18 / Con 14 / Wis 11 (or similar), take Melee Training (Dexterity), and pump Dex and Con thereafter. Damage will be slightly lower (3 less at level 30 relative to a Str 16 / Dex 16 or Str 18 / Dex 14 build) but will apply equally to ranged attacks. Skill Focus (Athletics), Agile Athlete, and magic items can make up for the poor Athletics skill that results from not pushing Strength. Sadly, Heavy Blade Mastery will be out of reach.
The above build will be very consistent and adaptable -- note that the Slayer can swap weapons as a minor action, so switching between Fullblade and Greatbow is easy. For melee, which should still be the main focus, charging is an excellent option; if you can find ways to make charging safer (Badge of the Berserker, etc.) or more powerful (Vanguard Weapon, Horned Helm, etc.) you will be glad.