using the following macro by equipping/unequipping t1 3 set and replacing one of the 3 with a T2 piece you can get a permanant 30-54 block value without having the 3 set T1 equipped or scarab equipped, you also don’t get the 3 set bonus until you equip 4 pieces.
/run print(('Block Value %.2f'):format(GetShieldBlock("player")))
Steps to replicate,
Make sure T1 set isn’t equipped, check block value
Equip 3 set T1, check block value (stays the same)
Equip 4 set T1, check block value (goes up by 30)
Go back to 3 set T1, check block value (its still 30 higher)
Replace one piece of T1 with a T2 item[not T2 shoulders/boots/pants/helm], check block value (its still 30)
Replace Styleen’s Impeding Scarab with any other trinket. (its still high)
seems semi permanent, rezoning resets to the correct value, after 5-10 minutes it resets, changing to a lower shield block shield resets the value as well.
Seems like its only applying when taking it off not when equipping it or when you equip 4 pieces.
Seems to work with Styleen’s Impeding Scarab as well, you won’t get the bonus unless you equip a different shield and then go back to your higher shield, changing your shield is the only “reset” you can replace the trinket and keep the shield block value.
Can you fix shield block value or is this working as intended? I mean i personally don’t mind having 187 shield block value whilst only wearing +74 shield block value gear and 264 strength (+13sbv) and +47 base shield block. (134 shield block) free 24 from Styleen’s Impeding Scarab and a free 30 from replacing t1 3 set with t2 item.
something doesn’t add up. 
Edit: must just be slow api, combat log testing shows it all working as intended.