Solutions from the comments:
uxterm- CtrlRightClick (context menu) and UTF-8 encoding.
xterm -u8- X resources: use a font specification with character set and econding fields set to
-iso10646-1
For X Window experts: pass a font specification with “-iso10646-1” afterexample, for xterm -fn (presumedlyX-class Xterm) and the Terminus font, you know wheremight add to ~/.Xresources
XTerm*font: -*-terminus-medium-r-normal--18-*-*-*-*-*-iso10646-1
To find it)the fonts and their font specs installed on your system see /usr/share/fonts/*/*.dir files. After editting ~/.Xresources, load them with xrdb -merge ~/.Xresources.