[Peace-Maker]

You'll need to create that weaponKB array yourself again, but the plugin itself is straight forward.

PHP Code:

new PlVers:__version = 5;
new Float:NULL_VECTOR[3];
new String:NULL_STRING[1];
new Extension:__ext_core = 68;
new MaxClients;
new Extension:__ext_sdktools = 184;
public Plugin:myinfo =
{
    name = "KnockBack",
    description = "Weapon Knock Back",
    author = "ýý¿ýýý",
    version = "1.0",
    url = ""
};
new String:weaponKB[28][2][64] =
{
    {
        "knife",
        "0.0"
    },
    {
        "glock",
        "1000.0"
    },
    {
        "usp",
        "1000.0"
    }
}
public __ext_core_SetNTVOptional()
{
    MarkNativeAsOptional("GetFeatureStatus");
    MarkNativeAsOptional("RequireFeature");
    MarkNativeAsOptional("AddCommandListener");
    MarkNativeAsOptional("RemoveCommandListener");
    VerifyCoreVersion();
    return 0;
}

ScaleVector(Float:vec[3], Float:scale)
{
    new var1 = vec;
    var1[0] = FloatMul(var1[0], scale);
    new var2 = vec[4];
    var2 = FloatMul(var2, scale);
    new var3 = vec[8];
    var3 = FloatMul(var3, scale);
    return 0;
}

MakeVectorFromPoints(Float:pt1[3], Float:pt2[3], Float:output[3])
{
    output[0] = FloatSub(pt2[0], pt1[0]);
    output[4] = FloatSub(pt2[4], pt1[4]);
    output[8] = FloatSub(pt2[8], pt1[8]);
    return 0;
}

bool:StrEqual(String:str1[], String:str2[], bool:caseSensitive)
{
    return strcmp(str1, str2, caseSensitive) == 0;
}

public OnPluginStart()
{
    CreateConVar("knockback_version", "1.0", "knockback plugin info cvar", 8448, false, 0.0, false, 0.0);
    HookEvent("player_hurt", EventHook:5, EventHookMode:1);
    return 0;
}

public Action:Player_Hurt(Handle:event, String:name[], bool:dontBroadcast)
{
    new Client = GetClientOfUserId(GetEventInt(event, "userid"));
    new Attacker = GetClientOfUserId(GetEventInt(event, "Attacker"));
    new var1;
    if (AliveCheck(Client) == 1) {
        decl String:k_weapon[32];
        GetEventString(event, "weapon", k_weapon, 32);
        new i = 0;
        while (i < 28) {
            new var2 = weaponKB[i][0][0];
            if (StrEqual(var2[0][var2], k_weapon, true)) {
                decl Float:Clientposition[3];
                decl Float:targetposition[3];
                decl Float:vector[3];
                GetClientEyePosition(Attacker, Clientposition);
                GetClientEyePosition(Client, targetposition);
                MakeVectorFromPoints(Clientposition, targetposition, vector);
                NormalizeVector(vector, vector);
                ScaleVector(vector, StringToFloat(weaponKB[i][0][0][4]));
                TeleportEntity(Client, NULL_VECTOR, NULL_VECTOR, vector);
            }
            i++;
        }
    }
    return Action:0;
}

public bool:AliveCheck(Client)
{
    new var1;
    if (Client > 0) {
        if (IsClientConnected(Client) == 1) {
            if (IsClientInGame(Client) == 1) {
                if (IsPlayerAlive(Client) == 1) {
                    return true;
                }
                return false;
            }
            return false;
        }
        return false;
    }
    return false;
}