6.124 (on YouTube)
Timanōr’s bloody shoulders bore me once,
And now, a shield, I hang beneath the eaves
Of Pallas’ shrine, Defender in the Fight.
I often knew the dust of iron war,
And ever warded death from him who bore.
Doubtless plenty of real-life mercenaries did make offerings on retirement to whatever deity they credited for their survival, and though I don't presently have access to a library to check, it's a fair bet that many of them commissioned inscriptions, a minority of which were surely in verse. These literary versions, though, are consciously participating in an extended conversation (which may nonetheless have intersected with and enriched actual inscriptional practice) between authors writing for publication and performance. The following poem by Nicias implicitly acknowledges that plenty of poets have tried their hand at the 'shield' trope already ('just like the others') -- and Nicias, a friend of Theocritus, comes very early in epigram's development as a literary genre.
6.127 (on YouTube)
Just like the others, I was always bound
To leave behind the hateful strife of War
And listen to the chorus of the girls
Beside the shrine of Artemis, the place
Where Epixenus dedicated me,
When pale old age began to sap his limbs.
Mnasalcas was a contemporary of Nicias.
6.264 (on YouTube)
The shield of Alexander, Phylleus’ son,
I hang here as a holy offering
To lord Apollo of the golden hair.
Worn is my rim and tired by constant war,
Worn too my boss, but courage makes me shine,
Courage I earned in arming that brave man
Who set me here. From when I first was made,
I never have been worsted or outdone.