Leave. Mastery Icons (and their sigils). Alone. The current ones that we have are part of the game's heritage, and they work well as an expanding design that grows ever more complex and detailed as your mastery increases. One of the main driving forces for me to attain MR28+ was the beautiful symbol and sigil of that tier. I worked for literally years to accomplish earning this, DO NOT CHANGE IT.
This applies to Eject Magazine/Tactical Reload/etc., the Synth mod set bonus, and the innate holster-reload that spearguns have. Usually (see below) everything works normally until my first death and revive in a mission, after which all of these effects stop working completely. While this is the only completely reproducible situation I've noticed, it also seems like they will just randomly stop working at other times, or just never work at all from the beginning of the mission.