Stats are random, so you can potentially find other weapons with the Frost skill on them. Unlike the Freeze spell, Frost on a weapon ignores the target's resistances, which is what makes it so effective. I only tried one Frost weapon my first game, but found it made fights too easy.
Replacing the sword will re-seal the ghost in the stone, and prevent it from killing most of the NPCs in the Dark Forest. If you want to keep the sword, you can use the duplication trick to copy it, or just wait until you have completed all the quests in the Dark Forest before removing it.
To copy an item; <span class='standouttext'>Spoiler : </span><span class='spoiler'>quick save the game, then drag an item out of your inventory, but not somewhere there is a red X. Without dropping first, quick load the game, then release the mouse button when it starts to load. This will produce a copy of the item on the ground, with the original still in your inventory.
There is a much easier method for items which can be stacked;
Drag a stack out of (or into) your inventory (or container) and hold down the control key before dropping. This will bring up the split stack pane; type in a negative number and hit enter (the checkmark will be greyed out). This can also be done in the trade window.</span>
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