You could tamp the effect down a bit. Rather than "spend 1 XP to a make a roll a 12," you could have "spend 1 XP to give +1 to a roll you just made. So it could turn a 6 into a soft hit or a 9 into a full hit. But a 5 or less is still going to be a miss, period. (And turning a 6 into a 7 really is costing 2 xp total.)
Additional potential XP use:
Spend 1 XP to negate (halve?) the damage you just took, but the GM picks one:
- You lose your footing, your grip, or your bearings
- Something breaks (your weapon, your shield, etc.)
- You're somehow imperilled: on fire, dazed, pinned, etc.