People around him were puzzled by his strange behavior.
The proposal struck me as odd.
I found his sudden change in attitude strange.
There was a strange object placed in that room.
He was being looked at with strange, disapproving stares by those around him.
不思議 highlights the mysterious or wondrous side of something, while 奇異 emphasizes oddness that can feel unsettling or out of place.
異様 describes something so abnormal it looks eerie or uncanny, whereas 奇異 covers a milder sense of strangeness that draws attention.
変 is a casual, everyday way to say something is 'weird', while 奇異 is a more literary or formal term for the same idea.
奇異 is a formal word often used to describe a reaction of surprise at something strange, while 奇 simply labels the quality of strangeness itself.
普通 means 'ordinary' or 'normal', the direct opposite of 奇異's sense of standing out as strange.
paradoxical incontinence
Compound of 奇 (ki, 'strange, unusual') and 異 (i, 'different, unusual'). The combination reinforces the sense of something being out of the ordinary.