The bug
Mobs summoning with the PatrolLeader tag don't have weapons and lack the illager banner
How to reproduce
Summoning a pillager with PatrolLeader set to 1
/summon minecraft:pillager ~ ~ ~ {PatrolLeader:1}→ ❌ The pillager lack the illager banner and haven't a weapons
You must add the ArmorItems to make them have a banner
No weapon is MC-86172
And, if you kill a pillager with "PatrolLeader" tag, you won't get a bad omen