Fencing Ace

Double strike on a 1/1 for two mana is a bet placed entirely on the rest of your deck. The body does nothing in a vacuum: a single point of toughness folds to almost any removal and dies to nearly every common blocker. What it offers is a multiplier, and multipliers want fuel. A single pump effect on a normal creature adds its bonus once; on a double striker, every point of power added gets dealt twice in a turn, so the math on combat tricks and equipment runs at double the usual rate. That is the entire design rationale for shipping the keyword on a frame this fragile: the toughness has to stay at one to keep the package honest, because a creature that survives nothing is the price you pay for an attacker that turns one Giant Growth into six damage. It also makes a natural home for any +1/+1 counter or aura the rest of the format provides, since the doubled output scales linearly with whatever you stack on it. The keyword has appeared on far more expensive and more durable bodies, but the cheap, all-or-nothing version captures what the expensive ones blur over: double strike is a payoff that exists to be enabled, and putting it on the smallest possible body forces the deck to do the work the card refuses to do alone.