Probably the oldest imagery of an animal carrying a sword in its mouth to fight with comes from, interestingly enough, The New Testament—specifically Revelations—or interpretations thereof.
One common feature of Christian iconography is association of Jesus with lambs. He is portrayed as a shepherd, ministering to his "flock" of disciples and followers; and he his also shown as a sacrificial lamb, who bleeds and dies like a traditional Hebrew sacrifice made to propitiate God. According to Revelations 5:6, Jesus in heavy appears as a lamb.
And I saw in the midst of the throne and of the four living creatures, and in the midst of the elders, a Lamb standing, as though it had been slain....
Later, in Revelations 19:11–16, Jesus appears again
And I saw the heaven opened; and behold, a white horse, and he that sat thereon called Faithful and True; and in righteous he doth judge and make war.
And his eyes [are] a flame of fire, and upon his head [are] many diadems; and he hath a name written which no one knoweth but he himself.
And he [is] arrayed in a garment sprinkled with blood: and his name is called The Word of God.
And the armies which are in heaven followed him upon white horses, clothed in fine linen, white [and] pure.
And out of his mouth proceedeth a sharp sword, that with it he should smite the nations: and he shall rule them with a rod of iron: and he treadeth the winepress of the fierceness of the wrath of God, the Almighty.
And he hath on his garment and on his thigh a name written, King of Kings and Lord of Lords.
Usually, this version of Jesus, carrying the sword in his mouth, is depicted as human.
However, since Jesus had already appeared in the narrative in the lamb form, there were occasional depictions of the rider Word of God, King of Kings and Lord of Lords as a sword-carrying lamb himself. It is an uncommon motif, but that iconography does exist.