Aegis Vanguard is part of Riftborne’s reference system and is documented here for patch 11.73. Source
Evidence status — confirmed: Unless noted otherwise, mechanics are verified against the installed patch 11.73 guide.
Aegis Vanguard is the Fighter directive path. It contains ten stages that progress automatically alongside the other directive tracks.
Level 5, Shock Spearhead, requires a victory over a defending fleet with more than 10,000 power. The installed directive data describes intermediate stages as guidance and progression milestones rather than separate combat bonuses.
Completing all ten stages grants the permanent Aegis Vanguard capstone: +8% fleet attack. A reference to “Aegis level 5” therefore identifies directive progress, not a 5% or half-strength version of the final buff.