Are the following sentences figurative language:

"With lies well steel'd with weighty arguments."

Yes -- the image created by "steel" and "weighty" is the point.

Thank you so much!

You're welcome.

Yes, the sentence "With lies well steel'd with weighty arguments" contains figurative language. The phrase "lies well steel'd" is a figure of speech known as a metaphor. In this metaphor, the word "steel'd" is used to mean fortified or strengthened, suggesting that the lies are made more convincing or persuasive by the addition of weighty arguments.