Open any page which displays a weapon with speed modifier 0 (for example War Axe). It can be a page of the base itself, or of a runeword eligible to be made in that base (in this case Call to Arms).
Notice that speed modifier is not displayed at all, while it should be listed as 0.
Compare it with another base weapon with non-zero speed (for example Double Axe) or with other bases on the runeword page.