Here's a mechanic that could work on a "gambler"-type job

Coin Flip
Weaponskill
Flips a coin, gaining a stack of Heads or Tails, up to three.
Maximum Charges: 3
Cast: Instant
Recast: 20s

One More!
Weaponskill
Reroll your last flipped coin.
Cast: Instant
Recast: 1.5s

Gil Toss
Weaponskill
Cost: 1 Coin
Delivers a ranged attack. Potency varies with the amount of Heads and Tails.
1 Tails: 120
1 Heads: 200
Cast: Instant
Recast: 2.5s

Gil Rush
Weaponskill
Cost: 2 Coins
Rushes target and delivers an attack. Potency varies with the amount of Heads and Tails.
Cannot be executed while bound.
2 Tails: 160
1 Tails, 1 Heads: 320
2 Heads: 480
Cast: Instant
Recast: 2.5s

Gil Slash
Weaponskill
Cost: 3 Coins
Delivers an attack. Potency varies with the amount of Heads and Tails.
3 Tails: 120
2 Tails, 1 Heads: 360
1 Tails, 2 Heads: 600
3 Heads: 840
Cast: Instant
Recast: 2.5s

Optimal Combos

Heads Heads Heads: Gil Slash: 840 Potency
Heads Heads Tails: Gil Slash/Gil Toss > Gil Rush: 600 Potency
Heads Tails Tails: Gil Toss > Gil Rush: 440 Potency
Tails Tails Tails: Gil Toss > Gil Toss > Gil Toss: 360 Potency