How to equip a fbx weapon to a fbx model

Questions
1

I was trying to load a sword in the right hand but I don’t see the sword. Please see my code below. Could you shed some lights on this please?

            fbxloader.load('models/fbx/guard/vanguard_t_choonyung.fbx', (fbx) => {
                actions = {};
                fbx.scale.set(0.01, 0.01, 0.01)
                fbx.position.set(0, 0, 0)
                guardMixer = new THREE.AnimationMixer(fbx)
                actions['default'] = guardMixer.clipAction(
                    fbx.animations[0]
                )

                fbx.traverse(function (object) {
                    if (object.isMesh) object.castShadow = true;
                });

                model = fbx;
                model.rotation.y = 3;

                skeleton = new THREE.SkeletonHelper(model);
                skeleton.visible = false;
                scene.add(skeleton);

                dirLight.target = model;
                fbxloader.load('models/fbx/guard/animations/Standing Idle.fbx', (fbx) => {
                    actions['idle'] = guardMixer.clipAction(
                        fbx.animations[0]
                    )
                    currentAction = 'idle';
                    activatedActions.push(currentAction);
                    actions['idle'].play();
                    fbxloader.load('models/fbx/guard/animations/Great Sword Walk.fbx', (fbx) => {
                        actions['walk'] = guardMixer.clipAction(
                            fbx.animations[0]
                        )
                        scene.add(model);
                        guardReady = true;
                    })
                })

                fbxloader.load("assets/weapons/fbx/sword/Scottish_Sword.FBX", function (fbxSword) {
                    scene.add(fbxSword);
                    fbxSword.scale.setScalar(0.015);
                    const rightHand = fbx.getObjectByName("mixamorigRightHand");
                    rightHand.add( fbxSword );
                })
            })