Guard should be rebalanced to have an extra -1 self damage. so if you hit yourself with guard it will deal 2 less than what it would without, most guard gameplay relies on trades based on using guard to trade hp with your opponent and benefit from the -1 difference. A lot of guard play also require guarding your own structures to benefit from guards unique mechanics, so by increasing self damage reduction to -2 total it helps give guard the slight edge against the opponent by benefiting from the difference in damage dealt