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I don't think there's a David with 8 toughness.
To the actual question, winning or losing a battle doesn't change the strength (*/) or toughness (/*) of a card, barring a rule or ability to that effect. Targeting a character with an increase, decrease, or toss ability will change their strength and toughness, and playing under the Experience Credit rule (mandatory for T2, optional for T1) increases characters 1/1 on a successful block (Evil Characters) or successful rescue (Heroes).
