If you save enough many spell picks, when you level up, you may reach the point where you have more spell picks than spells to pick. When this happens, the game only displays the number of spells you can pick, and if you choose all of them, the remaining number will be 0.

There is, however, a minor bug with this mechanic. If Set Portal and Return to Portal are both available to pick, however, the game will show it as 2 picks, but picking them will only count as 1. Therefore, it is necessarily the case that you will be left with 1 spell to choose.

Example: My Valkyrie had 6 spells available to pick at level up, including the portal spells. The game showed me having 6/6 spells to pick, but after choosing them all, I still had 1/6 remaining.

Fortunately, because you can save spell picks, this isn't a fatal bug and is only a minor one.

Lvl 6 Omnigun has only a KO effect assigned, only lvl 9 Omniguns or higher have crit chance assigned.
Message should also be "tweaks omnigun to make it faster and adds a KO attachment"
based on that i guess you use the wrong \data\strings\stringdata.dat or a weird \patches\patch.nnn file.

Actually, my understanding is that, in 1.0, the Omnigun Mark 6 (only) had a 5% Kill effect assigned. This led to players looking for ways to keep it when reaching the level at which it would "upgrade" to the Mark 7, where it became KO.

This Kill was changed to KO in a patch.

I forgot that I was playing a mod this time. You might be right about why this level of omnigun is kill instead of KO. The description when leveling up said it was tweaked to add a KO affect. But when I looked at the gun it states Kill.