[Phl 2:12-16 CSB] (12) Therefore, my dear friends, just as you have always obeyed, so now, not only in my presence but even more in my absence, work out your own salvation with fear and trembling. (13) For it is God who is working in you both to will and to work according to his good purpose. (14) Do everything without grumbling and arguing, (15) so that you may be blameless and pure, children of God who are faultless in a crooked and perverted generation, among whom you shine like stars in the world, (16) by holding firm to the word of life. Then I can boast in the day of Christ that I didn't run or labor for nothing.
[Phl 2:12-16 MGNT] (12) ὥστε ἀγαπητοί μου καθὼς πάντοτε ὑπηκούσατε μὴ ὡς ἐν τῇ παρουσίᾳ μου μόνον ἀλλὰ νῦν πολλῷ μᾶλλον ἐν τῇ ἀπουσίᾳ μου μετὰ φόβου καὶ τρόμου τὴν ἑαυτῶν σωτηρίαν κατεργάζεσθε (13) θεὸς γάρ ἐστιν ὁ ἐνεργῶν ἐν ὑμῖν καὶ τὸ θέλειν καὶ τὸ ἐνεργεῖν ὑπὲρ τῆς εὐδοκίας (14) πάντα ποιεῖτε χωρὶς γογγυσμῶν καὶ διαλογισμῶν (15) ἵνα γένησθε ἄμεμπτοι καὶ ἀκέραιοι τέκνα θεοῦ ἄμωμα μέσον γενεᾶς σκολιᾶς καὶ διεστραμμένης ἐν οἷς φαίνεσθε ὡς φωστῆρες ἐν κόσμῳ (16) λόγον ζωῆς ἐπέχοντες εἰς καύχημα ἐμοὶ εἰς ἡμέραν Χριστοῦ ὅτι οὐκ εἰς κενὸν ἔδραμον οὐδὲ εἰς κενὸν ἐκοπίασα
Paul is probably referring to the "Sword of the Spirit", as referenced in The book of Ephesians chapter 6 verse 17, when he says,'“holding firm to the word of life”?
New International Version (NIV)
Take the helmet of salvation and the sword of the Spirit, which is the word of God.
John 6:63 reads,
It is the Spirit who gives life; the flesh is no help at all. The words that I have spoken to you are spirit and life.
One can recognise from the above text that the "Spirit is life",and from Ephesians 6:17 that the Sword of the Spirit is the "Word of God".
If the Spirit is life, and the word of God is the sword of the Spirit,then i think it is reasonable to say that,when one takes a hold of the "Sword of the Spirit", they are in fact,
“Holding firm to the word of life” and also,
"Holding firm to the Sword of the Spirit"