For me, at least. I have been playing Warframe on and off for several years
Back when I was a newer player in 2015, I got my hands on a Machete from some event, maxed it out for Mastery XP, and sold it for Credits and to free up the weapon slot. Fast forward to now, and I am building a collection of all Warframes, weapons, etc., spending a lot on new slots. It is an arduous task, and will be so for some time, but doing some quick research on the Machete today, I have found that I cannot obtain another copy.
The Machete blueprint is currently only given out as a reward from the Daily Tribute. The Daily Tribute only gives weapon and warframe blueprints for the ones you have yet to master, as well as the trio of login weapons. As I mastered the Machete a long time ago, that means there is no method for me to obtain the Machete again.
This may sound like a 1st world Tenno problem, but I'm simply asking for DE to add a new way to get the Machete again. Maybe as an event reward?