Twice in the last week my weapon was changed in an Arena match.
I play on a galaxy s9 running 8.0.0
I went in with Divine Protector. The colors are still correct for that weapon. It is also the mana needed to use the weapon. But the weapon ability matches the weapon pictured, Flammifer.
Earlier in the week my Runic Blade was changed into Elder Bow. It was the same issue, the Runic Blade colors filled it, but used the Elder Bow ability.