The 'Regenerate +5 (+7.5 on Tau-Forged) Shields when you inflict an enemy with Blast Status' perk of the Topaz Archon Shard incorrectly applies the Shield Regeneration when adding to Overshields. Whenever inflicting Blast on an enemy, the Shard resets any currently active Overshields on a Warframe instead of giving +5 (or +7.5) Shield Points to your Overshields, resulting in the Topaz Shard synergizing extremely poorly when partnered with Augur Set Mods, the Brief Respite Aura Mod, and Warframe Abilities like Protea's Grenade Fan. Inflicting Blast on a target while at full Shields also restores no Shields.
This has been tested both with a Thermal Sunder Hildryn and an Epitaph, and inflicting Blast consistently resets Shields on the Warframe.
The video below shows in-game footage of the Overshield Reset happening in the Simulacrum (the bug occurs in missions as well.)