Who says 'seest' these days? Up until the early 20th century it was all the rage to tag 'est to the end of all manner of verbs, in grammatical terms I believe it is known as the second-person singular present tense suffix:

When thou seest an eagle, thou seest a portion of genius; lift up thy head!

William Blake
English engraver, illustrator, & poet (1757 - 1827)

But these days we reserve 'est solely for the superlative. We have lost the freedom to goest and makest the most of these little grammatical quirks and now thine 'est is relegated to the realms of religion and theatre. Oh wo betide, that I hath lost mine 'est!