Death guard rules interaction
Been away from the hobby for a long while now but recently came back to it, and I'm updating my death guard for the new ruleset (got their own codex, hoooray!)
Anyway, simple question, how does the Death Guard psychic power "Blades of Putrefaction" interact with the (common throughout the codex) special rule "Plague Weapon"?
As I read it, "Plague Weapon" allows me to reroll rolls of 1 to wound. "Blades of Putrefaction" adds 1 to all to wound rolls I make with the affected unit (it is a mandatory addition, unlike the "you can add 1" that is written in the "Veterans of the Long War" stratagem), and grants a bonus mortal wound for all to-wound rolls of 7 or higher made with plague weapons. The problem I see here is that, RAW, this psychic power prevents re-rolling 1's because any dice roll of 1 becomes counted as a 2, and thus ineligible for reroll.
Am I misreading something/missing a rule somewhere or is this the case and thus instead of a straight bonus blades of putrefaction is a trade-off.